Year	per 1,000 people
1960	28.3
1962	26
1966	20.3
1970	20.3
1976	15.2
1977	14.3
1978	13
1979	14.5
1980	14.9
1984	15.1
1989	15.2
1990	14.6
1991	15.4
1992	15.5
1993	13.7
1994	14.5
1995	13.3
1996	13.9
2000	13.5
2001	13.3
2002	13.2
2003	13.2
2004	13.2
2005	13.1
2006	12.5
2007	13.4
2008	12.8
2009	12.5
2010	12
2011	10.6
2012	10.4
2013	10.5
2014	9.3
2015	9.4
2016	9.3
2017	9
2018	8.3
2019	8.2
2020	8.4
2021	7.7
2022	7.5