Year	US Dollars adjusted for inflation)
1989	6.32
1990	6.08
1991	6.11
1992	6.69
1993	7.11
1994	7.04
1995	7.44
1996	7.77
1997	8.16
1998	8.46
1999	9.17
2000	9.71
2001	10.12
2002	10.57
2003	11.07
2004	11.52
2005	11.61
2006	11.92