Year	US Dollars adjusted for inflation)
1989	12.68
1990	12.38
1991	12.13
1992	12.28
1993	12.86
1994	12.71
1995	13.05
1996	13.72
1997	14.82
1998	15.47
1999	15.97
2000	16.39
2001	16.7
2002	17.22
2003	17.67
2004	18.78
2005	19.49
2006	20.27