3. Miscellaneous Financial Information

Research and development expenses totaled $1,214 million in 2019, $1,116 million in 2018, and $1,063 million in 2017.

Net income included before-tax aggregate foreign exchange transaction losses of $104 million and $138 million in 2019 and 2018, respectively, and a gain of $6 million in 2017.

In 2019, 2018, and 2017, net income included gains of $523 million and $107 million, and a loss of $10 million, respectively, attributable to the combined effects of LIFO inventory accumulations and drawdowns. The aggregate replacement cost of inventories was estimated to exceed their LIFO carrying values by $9.7 billion and $8.2 billion at December 31, 2019, and 2018, respectively.

Crude oil, products and merchandise as of year-end 2019 and 2018 consist of the following: