Year	per 1,000 people
1960	0.185
1970	0.232
1975	0.233
1980	0.285
1981	0.344
1982	0.342
1986	0.351
1990	0.462
1991	0.48
1992	0.491
1993	0.502
1994	0.512
1995	0.524
1996	0.541
1997	0.555
1998	0.568
1999	0.582
2000	0.595
2001	0.605
2004	0.682
2005	0.725
2007	0.703
2008	0.721
2009	0.734
2010	0.745
2011	0.767
2012	0.796
2013	0.817
2014	0.841
2015	0.876
2016	0.917
2017	0.961
2018	0.947
2019	1.084