Year	US Dollars adjusted for inflation)
1989	21.64
1990	22.43
1991	22.27
1992	22.84
1993	23.2
1994	23.88
1995	24.5
1996	25.07
1997	25.7
1998	26
1999	26.37
2000	27.06
2001	27.55
2002	27.95
2003	28.29
2004	28.49
2005	28.88
2006	29.49