Year	US Dollars adjusted for inflation)
1989	8.46
1990	8.78
1991	8.04
1992	7.89
1993	7.91
1994	8.08
1995	8.41
1996	8.68
1997	8.59
1998	8.63
1999	8.91
2000	9.26
2001	9.88
2002	10.12
2003	10.62
2004	10.98
2005	11.46
2006	12.03