Year	US Dollars adjusted for inflation)
1980	10.07
1981	10.29
1982	10.55
1983	11.09
1984	11.84
1985	11.78
1986	12.68
1987	14.03
1988	14.92
1989	15.39
1990	16.02
1991	16.72
1992	17.91
1993	18.64
1994	19.2
1995	19.68
1996	19.44
1997	19.86
1998	19.01
1999	19.84
2000	21.13
2001	21.01
2002	21.59
2003	22.42
2004	23.75
2005	25.08