Year	per 1000 people
1970	3.2
1971	3.3
1972	3.32
1973	3.4
1974	3.475
1975	3.63
1976	3.72
1977	3.81
1978	3.95
1979	4
1980	4.123
1981	4.212
1982	4.319
1983	4.333
1984	4.471
1985	4.611
1986	4.699
1987	4.808
1988	4.868
1989	4.971
1990	4.926
1991	4.898
1992	4.726
1993	5.003
1994	4.899
1995	4.792
1996	4.457
1997	5.192
1998	5.042
1999	3.768
2000	4.731
2001	4.295
2002	3.907
2003	4.089
2006	4.65
2007	4.538
2008	4.663
2009	4.794
2010	4.289
2011	4.377
2012	4.406
2013	4.477
2014	4.776