content_image/1025629.jpg
## Benefit Obligations, Fair Value of Plan Assets and Funded Status 

The following tables provide a reconciliation of the changes in the pension and retiree medical and other postretirement benefits obligations, fair value of plan assets and a statement of funded status as of December 31, 2018 and 2017: 

<img src='content_image/1025629.jpg'>

$^{(1)}$ The December 31, 2018 and 2017 pension actuarial (gain) loss primarily relates to changes in our weighted average discount rate and mortality assumptions and, in 2018, changes to our retirement rate assumptions. 

$^{(2)}$ The December 31, 2018 and 2017 retiree medical and other postretirement benefits actuarial (gain) loss primarily relates to weighted average discount rate assumption changes and, in 2018, changes to our medical trend and per capita claim assumptions. 

$^{(3)}$ During 2018, we contributed $475 million to our defined benefit pension plans, including supplemental contributions of $433 million in addition to a $42 million minimum required contribution. During 2017, we contributed $286 million to our defined benefit pension plans, including supplemental contributions of $261 million in addition to a $25 million minimum required contribution. 

