Year	per 1,000 people
1960	0.077
1970	0.082
1980	0.176
1983	0.2
1986	0.329
1988	0.342
1992	0.234
1996	0.171
2004	0.493
2009	0.487
2010	0.56
2011	0.554
2012	0.487
2013	0.571
2015	0.743
2016	0.731
2018	0.791