Year	per 1000 people
1970	1.8
1971	1.9
1972	1.9
1973	1.9
1974	2
1975	2
1976	2.1
1977	2.1
1978	2.1
1979	2.2
1980	2.3
1981	2.3
1982	2.4
1983	2.5
1984	2.5
1985	2.6
1986	2.6
1987	2.6
1988	2.7
1989	2.7
1990	2.7
1991	2.7
1992	2.7
1993	2.9
1994	2.9
1995	3
1996	3
1997	3.1
1998	3
1999	3.1
2000	3.4
2001	3.4
2002	3.5
2003	3.513
2006	3.58
2007	3.61
2008	3.625
2010	3.585
2011	3.624
2012	3.663
2013	3.677