Year	Years
1980	4.539
1981	3.828
1982	3.787
1983	4.21
1984	6.596
1985	8.412
1986	6.743
1987	5.931
1988	5.99
1989	5.771
1990	5.844
1991	5.494
1992	5.563
1993	4.824
1994	4.75
1995	5.246
1996	5.013
1997	4.441
1998	3.851
1999	3.849
2000	3.411
2001	3.876
2002	3.456
2003	3.803
2004	3.543