On January 1, 2013, Medical Transport Company's accumulated postretirement benefit obligation was $50 million. At the end of 2013, retiree benefits paid were $5 million. Service cost for 2013 is $4 million. Assumptions regarding the trend of future health care costs were revised at the end of 2013, causing the actuary to revise downward the estimate of the APBO by $3 million. The actuary's discount rate is 6%.