Year	per 1,000 people
1960	0.34
1965	0.378
1970	0.453
1975	0.46
1980	0.416
1981	0.426
1984	0.637
1988	0.471
1990	0.657
1995	0.82
1997	0.856
2003	0.384
2005	0.498
2006	0.491
2007	0.525
2008	0.646
2009	0.7
2010	0.724
2011	0.808
2012	0.854
2013	0.89
2014	0.885
2015	0.92
2016	0.941
2017	0.975
2018	0.664