Year	US Dollars adjusted for inflation)
1989	12.22
1990	11.25
1991	10.34
1992	9.21
1993	8.82
1994	9.07
1995	9.99
1996	10.7
1997	11.87
1998	12.6
1999	12.99
2000	14.63
2001	15.69
2002	16.69
2003	17.6
2004	18.92
2005	20.35
2006	21.5