Year	per 1,000 people
1960	0.170626997947693
1970	0.199000000953674
1981	0.275599986314774
1987	0.3091000020504
1990	0.2497999966
2000	0.3
2001	0.39
2002	0.39
2003	0.39
2004	0.39
2005	0.42
2006	0.42
2007	0.42
2008	0.42
2009	0.42
2010	0.43
2011	0.44
2012	0.53
2013	0.53
2014	0.5
2015	0.5
2016	0.5
2017	0.39