Year	current US$
1990	4606930004.90844
1991	4753947346.15313
1992	5554457505.49873
1993	4460810887.48823
1994	2975721635.40206
1995	2852138756.68603
1996	3757384949.02242
1997	4660162371.75877
1998	4798210203.62063
1999	5154129863.60211
2000	5779061282.12926
2001	6535218682.20466
2002	7176301985.72477
2003	7697442217.61603
2004	8609155809.12215
2005	9858389922.9027
2006	11990966321.0459
2007	14349845216.8028
2008	17523218923.8192
2009	19218064606.2231
2010	22931474394.867
2011	24534799563.9935
2012	28996204124.3027
2013	34363835424.6635
2014	36725091501.2956
2015	38965340068.7833
2016	29768358959.1752
2017	25500125316.9064
2018	20503641225.9055