Year	per 1,000 people
1960	1.3
1961	1.2
1962	1.3
1963	1.3
1964	1.4
1965	1.4
1966	1.4
1967	1.5
1968	1.5
1969	1.6
1970	1.6
1971	1.7
1972	1.7
1973	1.9
1974	2
1975	2
1976	2.1
1977	2.2
1978	2.3
1979	2.3
1980	2.4
1981	2.5
1982	2.6
1983	2.8
1984	2.9
1985	2.9
1986	3.1
1987	3.3
1990	3.333
1991	3.584
1992	3.697
1993	3.798
1994	3.803
1995	3.841
1996	3.842
1997	3.957
1998	4.091
1999	4.195
2005	4.999
2006	5.366
2007	5.609
2008	5.711
2009	5.819
2010	5.803
2011	5.829
2012	5.823
2013	5.84
2014	5.883
2015	5.91
2016	6.137
2017	6.102
2018	6.161
2019	6.247
2020	6.306