On January 1, 2021, Medical Transport Company’s accumulated postretirement benefit obligation was $25 million. At the end of 2021, retiree benefits paid were $3 million. Service cost for 2021 is $7 million. Assumptions regarding the trend of future health care costs were revised at the end of 2021, causing the actuary to revise downward the estimate of the APBO by $1 million. The actuary’s discount rate is 8%. Determine the amount of the accumulated postretirement benefit obligation at December 31, 2021.