Year	per 1,000 people
1960	5.72566366195679
1970	5.09359979629517
1980	4.4047999382019
1990	4
1993	3.8838999271
1995	3.6
1996	3.9400000572
2000	3.5
2001	3.4
2002	3.4000000954
2003	3.4
2004	3.4
2006	3.2
2007	3.2
2008	3.2
2009	3.2
2010	2.92
2011	2.9
2012	2.86
2013	2.85
2014	2.76
2015	2.83
2017	2.96