Year	current US$
1970	2692.518583939002
1971	2843.5399957872537
1972	3265.2180370639217
1973	3961.972558070396
1974	5350.456670308883
1975	5800.844572446866
1976	6205.381180075187
1977	6336.903279767912
1978	6735.988548947082
1979	7428.288831915116
1980	8172.988545513886
1981	9728.451801168647
1982	10258.18127897959
1983	9380.934154423318
1984	10074.815059686414
1985	9142.59600268097
1986	9054.964451801652
1987	9257.534951423997
1988	11456.179241025797
1989	14164.744703550394
1990	14199.383859081749
1991	14632.708623358572
1992	14470.310040095408
1993	13945.398323154184
1994	14441.539445454846
1995	16118.046539003866
1996	17458.738747899875
1997	18756.052700855456
1998	17083.68284849468
1999	16493.576034341004
2000	17264.574828302906
2001	15632.6872788808
2002	16161.318353681801
2003	18933.24808015385
2004	24524.49803418043
2005	26918.779481810336
2006	28348.20663741566
2007	31382.239363974197
2008	38072.675189691385
2009	33482.73190258833
2010	40434.73569605864
2011	48363.135465754196
2012	53605.7387158548
2013	53871.55493401909
2014	48732.92492527929
2015	44512.59602918417
2016	39077.68931747156
2017	42069.085147269165
2018	44204.125502182455
2019	42130.89463661009
2020	40036.445821923124
2021	45710.890450597406