Year	US Dollars adjusted for inflation)
1980	6.2
1981	6.82
1982	7
1983	7.52
1984	8.17
1985	8.64
1986	9.33
1987	9.64
1988	9.76
1989	9.88
1990	10.24
1991	10.83
1992	11.43
1993	12.08
1994	12.67
1995	13.48
1996	14.35
1997	15.09
1998	15.89
1999	16.63
2000	17.4
2001	18.15
2002	18.67
2003	19.09
2004	19.56
2005	20.19