Year	US Dollars adjusted for inflation)
1989	8.51
1990	8.36
1991	7.76
1992	8.23
1993	8.39
1994	9.07
1995	9.45
1996	10.09
1997	10.83
1998	11.51
1999	11.79
2000	12.08
2001	12.48
2002	13.46
2003	14.38
2004	14.9
2005	15.31
2006	16.13