Comment: 47 year old numbers

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47 year old numbers

Hydrogen content of Earth's atmosphere:

520 ppb (parts per billion) with a trend of +1.2 ± 0.8 ppb/yr, measured from 1994 to 1998 - Simmonds et al. (2000)

531 ppb with a trend of -2.3 ± 0.1 ppb/yr, measured from 1991 to 1997 - Novelli et al. (1999)