Year	Years
1980	11.01
1981	10.69
1982	9.424
1983	8.916
1984	8.28
1985	6.28
1986	5.286
1987	4.415
1988	3.564
1989	3.273
1990	3.389
1991	3.845
1992	4.863
1993	4.678
1994	4.838
1995	4.822
1996	4.61
1997	4.81
1998	4.741
1999	4.458
2000	4.663
2001	3.956
2002	3.5
2003	2.936
2004	2.461