At the conclusion of what has been an eventful period for our company, Rusneftegaz held our annual general meeting on 8 April, with several figures from our organization convening in Moscow to discuss both our financial results and our future plans. The event centered upon the disclosure of our consolidated financial statements for 2015 earlier this week, which were unanimously approved in conjunction with our annual report. All the data published in these documents were prepared in accordance with International Financial Reporting Standards, also known as known as IFRS, and were externally audited to verify the reliability of our fiscal reporting. Whilst this was the principal focus of the convention, there were also a number of other motions passed, including maintaining the services of each member of our board of directors and reappointing our existing third-party auditor. In a similar vein, our stakeholders also voted to make no changes to the composition of our audit committee, in the opinion that that no amendments were necessary. However, our shareholders once again opted to forego any dividend for the economic performance we recorded last year, believing that it was in the long-term interests of Rusneftegaz to reinvest these funds in future projects.
Taking this into account, we overcame significant detrimental macroeconomic factors in the last financial year to increase our reported net profit from $122,5 million to $153,7 million, despite a fall in revenue from $552,9 million to $431,2 million. Over the course of the reporting period, there has been a consequential devaluation in our functional currency, the Russian ruble, and a global depreciation in commodity prices. However, our management has mitigated this through our extensive electricity generation program, which has led to revenue earned through the sector escalating from $184,3 million to $233,5 million, and also becoming the largest segment within our group of companies. Petroleum production only attributed to $197,7 million of our earned revenue, compared to $368,6 million in 2014, with oil output also diminishing from 8,35 million barrels per year to a total of 5,88 million barrels produced last year.
However, this abatement is part of our strategy in response to the fall in oil prices, and we have managed to preserve the integrity and profitability of our oil sector whilst retaining unextracted oil reserves for deployment in the future. The fulcrum of the relative prosperity of our petroleum division is largely as a result of a material reduction in mineral extraction taxes from $179,3 million to $28,2 million, due to some of our oilfields now being exempt from the tariff. The decline in the value of the Russian ruble was also responsible for falls in our labor costs from $40,1 million to $38,7 million, and maintenance charges from $11,5 million to $9,9 million. There were increases in other costs affiliated with crude oil extraction, including a rise in transportation charges from $7,1 million to $8,2 million, by virtue of oil deliveries inside the European Union.
Likewise, our total electricity output also fell from 11,53 TWh in 2014 to 11,39 TWh in 2015, although in contrast the net profits from our generation division rose to $37,1 million from $15,5 million the year prior. This was in spite of a stagnation in our fuel costs at $115,0 million, rising $0,2 million from $114,8 million, and in transmission costs, which were maintained at $1,7 million across both periods. There was, however, a sizable decrease in our administrative costs in 2015, which is composed of the wages of all our office-based staff, legal fees and insurance premiums, from $17,2 million to $9,0 million. Overall, for the year, our earnings per share equated to $122 per share, and our revenue per share amounted to the equivalent of $553 per share.
Rusneftegaz utilized these earned funds to invest $87,2 million in new assets, compared to an expenditure of $29,5 million the year before, mitigating a $28,6 million loss from depreciation and a further $16,0 million loss from mineral depletion. These costs represent an increase from 2014, where the total amount of our depreciation, depletion and amortization was reported at $40,1 million, although the aggregate of our impaired assets lowered from $2,3 million to $2,1 million. The total value of our property, plant and equipment nonetheless receded during the period from $713,8 million to $586,8 million because of a $172,4 million loss arising from fluctuations in foreign exchange rates, which was a component of the $254,5 million depression from currency conversion differences we recorded during the year, although the book value of all our property, plant and equipment did rise by $2,9 million following revaluation.
The contraction in the value of the ruble did not have as considerable of an impact as it did in 2014, where the total deflation was valued at $754,4 million. The continuation of the fall has led to the total value of our assets falling from $851,2 million to $695,2 million. This included a decrease in the amount of cash we recorded from $107,7 million to $82,8 million, with total foreign exchange losses valued at $93,6 million. This offset gains from our cash flows deriving from operations, financing and investment of $68,7 million. Of this figure, operating activities accounted for a total increase of $201,5 million, up from $167,1 million the year before, resulting in a decrease in our cash flow per share from $167 per share in 2014 to $131 in per share in 2015.
Along with cash and cash equivalents, Rusneftegaz also recognizes other non-fixed assets including those that are held specifically for sale, the balance of which remained the same at $5,0 million, and also trade and other receivables, the value of which fell from $22,0 million to $11,4 million. The only element of our current assets to increase in value during the year was our inventory, the volume of which ascended almost seven-fold from $1,1 million to $7,5 million, composed mostly of crude oil and coal, but also spare parts and other petrochemical products. The monetary worth of the majority of our non-current assets also descended, with the book value of all our intangible assets falling from $0,2 million to $0,1 million as a result of currency translation differences, although a nominal rise in the value of our derivative financial instruments to $0,7 million was a notable exception.
Of the $695,2 million of our total assets, $588,4 million are classified as non-current, with the remaining $106,4 million regarded as current. In comparison, $715,4 million of our assets were considered non-current assets in 2014, and $135,8 million of our assets were reported as current. Between each of our sectors, $393,9 million of our assets are affiliated with electricity generation, an expansion from $300,4 million the year before, and an additional $275,7 million are utilized in relation to petroleum production, compared to $431,5 million in 2014. Likewise, Rusneftegaz can also report $87,0 million in liabilities at the end of the financial year, down from $137,6 million, of which $40,3 million is associated with our power generation division, and $45,1 million is correlated with our oil operations. In both years, current liabilities exceed the total of non-current liabilities, with $52,8 million of short-term and $34,2 million of long-term liabilities recognized in our financial statements, compared to $102,2 million and $35,4 million respectively the year before.
On 31 December 2015, the largest component of our reported liabilities is accounts payable at $47,6 million, which inflated from $27,6 million on 31 December 2014, and provisions appraised at $23,4 million. This particular liability is an estimation of the future financial burden of fulfilling Russian regulatory requirements once our oil extraction licenses have expired, and decreased in value solely as a result of currency fluctuations in which the approximated charge is calculated. On the other hand, there were increases in our taxes payable from $3,9 million to $5,2 million, and also in deferred tax liabilities, which rose to $10,8 million from $4,0 million.
Moreover, the value of our recognized deferred tax assets also increased from $0,7 million to $0,8 million, with our heightened profits having consequentially caused rises in almost all of our taxation assets, liabilities and charges. The largest single tax expense recorded during the financial year was income tax, which rose from $24,8 million to $32,7 million. Along with deferred tax liabilities, our organization also recognized a current liability of $5,2 million for taxes and royalties due within the next financial year, with the figure climbing from $3,9 million in 2014. The magnitude of our foreign sales resulted in an export duty charge of $8,0 million, which was reported as a component of our cost of sales in our statement of profit or loss and other comprehensive income. This is in conjunction with other taxes that are not income tax, which deflated from $5,3 million to $4,8 million.
Overall, the continued uncertainty in worldwide commodity prices is likely to ensure that the financial performance of our petroleum division remains not as positive as in previous periods. Thus, our management board has undertaken an extensive plan to mitigate the effects of more challenging economic conditions, primarily by accelerating the volume of investments made in electricity infrastructure to establish greater efficiency and profitability over the next five years. In addition, we also plan to continue our existing strategy of managing our levels of oil extraction to maintain the profitability of this segment in the immediate term, whilst preserving the integrity of our oil reserves for the future when commodity process shall be expected to be higher, and will cultivate greater revenues. Said agenda for the short-term is also encompassed in a greater strategy for our long-term prosperity, involving our organization becoming one of the largest energy companies in the Russian Federation by the end of the next decade through an aggressive expansion program that is currently being implemented.