Year	current US$
1988	3000000
1989	2000000
1990	4000000
1991	10000000
1992	24000000
1993	30000000
1994	11000000
1995	21000000
1996	18000000
1997	17000000
1998	24000000
1999	18000000
2000	22000000
2001	26000000
2002	27000000
2003	28000000
2004	17000000
2005	19000000
2006	18000000
2007	22000000
2008	27000000
2009	25000000
2010	30000000
2011	73000000
2012	52000000
2013	35000000
2014	32000000
2015	40000000
2016	49000000
2017	46000000
2018	47000000
2019	41000000
2020	125000000
2021	115000000
2022	111000000
2023	106000000