Year	US Dollars adjusted for inflation)
1980	6
1981	6.04
1982	6.13
1983	6.3
1984	6.57
1985	6.87
1986	7.14
1987	7.32
1988	7.51
1989	7.73
1990	7.29
1991	6.88
1992	7.17
1993	7.16
1994	7.08
1995	7.85
1996	7.73
1997	8.16
1998	8.13
1999	7.58
2000	7.56
2001	7.35
2002	7.51
2003	7.35
2004	7.57
2005	7.66