Book value Percent Market value Percent Yield to Book Market Maturity Year (millions) of total (millions) of total Maturity values values 2019 $920 0.40 836.64 0.40 2.229% 0.89% 0.90% 2021 1,380 0.60 1,243.79 0.60 2.845% 1.71% 1.70% Total $2,300 1.00 $2,080.43 1.00 2.60% 2.60%