Year	U.S. dollars (Units)
1980	1421.836
1981	1763.344
1982	1784.577
1983	1849.427
1984	1839.915
1985	1965.139
1986	2284.039
1987	2823.157
1988	1389.823
1989	800.859
1990	967.145
1991	972.175
1992	983.575
1993	995.061
1994	1060.707
1995	1133.162
1996	1186.162
1997	1080.812
1998	1028.169
1999	1043.174
2000	1202.891
2001	1236.897
2002	1305.087
2003	1208.885
2004	1361.499
2005	1510.392
2006	1726.028
2007	2016.052
2008	2557.211
2009	2557.267
2010	2806.685