Year	current US$
1977	3851851.8518518517
1978	3925925.925925926
1979	3848148.148148148
1980	3959259.259259259
1981	4274074.074074074
1982	4318518.518518519
1983	4714814.814814814
1984	4077777.7777777775
1985	4914814.814814814
1986	5177777.777777777
1987	6111111.111111111
1988	6651851.851851852
1989	7025925.925925925
1990	7655555.555555555
1991	7981481.481481481
1992	8318518.518518518
1993	8585185.185185185
1994	8459259.25925926
1995	8600000
1996	9237037.037037037
1997	10481481.481481481
1998	10800000
1999	11311111.11111111
2000	11614814.814814813
2001	11322222.222222222
2002	12229629.62962963
2003	12900000
2004	12737037.037037035
2005	15199999.999999998
2006	16070370.37037037
2007	17540740.74074074
2008	17614814.814814813
2009	15418518.518518517
2010	15770370.37037037
2011	20981481.48148148
2012	24059259.259259254
2013	19670370.37037037
2014	19870370.37037037
2015	20781481.48148148
2016	21729629.629629627
2017	25492592.59259259
2018	27029629.629629627
2019	28429629.629629627
2020	32170370.37037037
2021	33340740.74074074
2022	36503703.7037037
2023	38922222.22222222