Year	US Dollars
1990	16619430951.2246
1991	18043770192.34609
1992	16680760657.2285
1993	17324636902.4199
1994	19223422149.9024
1995	19596098214.2674
1996	22218438395.14429
1997	22958977987.8155
1998	23560487734.4716
1999	23935719835.7934
2000	23677360610.3374
2001	24702389994.3105
2002	22998833317.8117
2003	19555221828.0102
2004	18720330564.82189
2005	18240745523.4703
2006	17964450079.34999
2007	17560507544.0597
2008	14236621918.4496
2009	15241250146.5722
2010	17490614681.7245
2011	20019030049.3674
2012	23679007713.451
2013	26411380999.2275
2014	27612120849.8848
2015	28221755179.6087
2016	29240313910.6288
2017	30511488208.2313