Year	US Dollars adjusted for inflation)
1980	10.76
1981	11.22
1982	9.68
1983	9.01
1984	9.13
1985	8.4
1986	8.47
1987	8.69
1988	8.95
1989	9.54
1990	9.57
1991	9.96
1992	10.82
1993	11.34
1994	11.74
1995	12.88
1996	13.58
1997	14.29
1998	14.54
1999	14.16
2000	14.57
2001	14.39
2002	14.44
2003	14.57
2004	15.16
2005	15.57