Year	Years
1980	2.734
1981	4.78
1982	3.5
1983	3.04
1984	4.229
1985	4.616
1986	5.28
1987	6.091
1988	4.118
1989	4.445
1990	5.219
1991	4.226
1992	4.925
1993	5.367
1994	5.617
1995	5.017
1996	5.228
1997	5.509
1998	6.456
1999	6.986
2000	5.642
2001	4.77
2002	4.328
2003	3.91