1/27.5 = 3.6% 你看一下RMD life table

https://www.fidelity.com/bin-public/060_www_fidelity_com/documents/UniformLifetimeTable.pdf

72 73 74 75 76 77 78 79 80 81 82 83 

27.4 26.5 25.5 24.6 23.7 22.9 22.0 21.1 20.2 19.4 18.5 17.7

每老一歲，RMD比例大一點，但是總和也應該少一點，如果你想用spreadsheet精算，have at it.