Year	US Dollars
1990	10335488288.8861
1991	11103770081.7743
1992	11808600177.1653
1993	13946736626.8469
1994	14298091283.1527
1995	15048394846.2952
1996	15614361554.4096
1997	15732861594.1463
1998	15236246150.5457
1999	15594824868.7542
2000	16064179059.2884
2001	16465003682.0461
2002	16809480086.6135
2003	17831466403.2918
2004	18607111612.241
2005	19316953886.4477
2006	20676043978.93209
2007	21529206367.7065
2008	22003986383.7655
2009	20901239121.0555
2010	21256914960.4109
2011	22187396305.326
2012	22876869414.5867
2013	23127291087.6545
2014	23752061681.931
2015	23989472607.3126
2016	24343735866.4477
2017	25108223022.9429