Year	current US$
1970	155.08787539790816
1971	158.325532358196
1972	134.74092833275256
1973	141.95485460165756
1974	171.61772719257036
1975	182.38011715267413
1976	192.4779037859605
1977	218.11050754051945
1978	239.47124824515942
1979	266.9632410353533
1980	271.9185362593986
1981	292.124774997018
2009	404.6013546769843
2010	506.922383976213
2011	568.5774104983402
2012	607.6121178130627
2013	598.8995846163791
2014	577.2601843509807
2015	550.241360031403
2016	485.79222940444083
2017	498.04122115479777
2018	467.28603443262836
2019	469.4777601093305
2020	476.8990597364072
2021	339.68211440290645