Year	US Dollars adjusted for inflation)
1980	8.56
1981	8.78
1982	8.88
1983	9.4
1984	10.05
1985	10.17
1986	10.55
1987	11.1
1988	11.76
1989	12.31
1990	12.16
1991	12.14
1992	12.58
1993	13.82
1994	14.73
1995	16.86
1996	15.65
1997	16.14
1998	15.48
1999	16.62
2000	18.59
2001	16.77
2002	17.81
2003	18.49
2004	19.85
2005	20.89