That 0.11 mSv/year figure was the peak value in 1963. Says so the 2008 UNSCEAR report (page 4), which puts the global average residual contribution of atmospheric testing at 0.005 mSv/year, and that of dispersed Chernobyl fallout at 0.002 mSv/year (reduced from 0.04 mSv/year in 1986).

_{*Lunatic*, n.
One whose delusions are out of fashion.}