tax benefit increased by $650 million between year-over-year periods from $2.32 billion in 2016 to $2.97 billion in 2017. The U.S. tax benefit for 2017 included a $2.02 billion benefit from U.S. tax reform, which primarily reflected the remeasurement of U.S. deferred tax assets and liabilities, and a reduction of $1.37 billion as result of the impact of a decrease in losses before tax of $3.88 billion. International income before tax increased from $2.16 billion in 2016 to $9.66 billion in 2017. This $7.50 billion increase was primarily driven by the effect of higher crude oil prices and gains on asset sales primarily in Indonesia and Canada. The higher crude prices primarily drove the $2.34 billion increase in international income tax expense between year-over-year periods, from $588 million in 2016 to $2.93 billion in 2017. Refer also to the discussion of the effective income tax rate in Note 18 on page 75.

The decline in income tax expense in 2016 of $1.86 billion is consistent with the decline in total income before tax for the company of $7.00 billion. U.S. losses before tax increased from a loss of $2.88 billion in 2015 to a loss of $4.32 billion in 2016. This $1.44 billion increase in losses was primarily driven by the effect of lower crude oil prices. The increase in losses had a direct impact on the company’s U.S. income tax benefit, resulting in an increase of $624 million between year-over-year periods, from a tax benefit of $1.69 billion in 2015 to a tax benefit of $2.32 billion in 2016. International income before tax was reduced between calendar years from $7.72 billion in 2015 to $2.16 billion in 2016. This $5.56 billion decline was also primarily driven by the effect of lower crude oil prices. This effect drove the $1.24 billion reduction in international income tax expense between year-over-year periods, from $1.83 billion in 2015 to $588 million in 2016. Refer also to the discussion of the effective income tax rate in Note 18 on page 75.

Liquidity and Capital Resources

Sources and uses of cash

Cash flow from operations increased $7.7 billion in 2017 primarily due to higher crude oil prices. The company also continued to reduce cash outlays and increase asset sales. Progress on these actions during 2017 included:

Reducing cash capital expenditures to $13.4 billion, a 26 percent decrease compared to 2016,

Reducing operating and administrative expenses by $1.1 billion, a 4 percent decrease compared to 2016, and

Realizing net proceeds from asset sales of $5.2 billion during 2017.

The strength of the company’s balance sheet enabled it to fund any timing differences throughout the year between cash inflows and outflows.

Cash, Cash Equivalents and Marketable Securities Total balances were $4.8 billion and $7.0 billion at December 31, 2017 and 2016, respectively. Cash provided by operating activities in 2017 was $20.5 billion, compared with $12.8 billion in 2016 and $19.5 billion in 2015, reflecting higher crude oil prices. Cash provided by operating activities was net of contributions to employee pension plans of approximately $1.0 billion in 2017 and $0.9 billion in both 2016 and 2015. Cash provided by investing