Year	US Dollars
1990	19380
1991	19390
1992	19710
1993	20530
1994	21660
1995	22550
1996	23110
1997	24310
1998	25240
1999	26720
2000	28420
2001	29220
2002	30070
2003	31390
2004	33020
2005	35390
2006	37400
2007	38860
2008	39680
2009	38120
2010	39230
2011	40780
2012	41400
2013	43430
2014	44780
2015	43960
2016	44230
2017	46070