Year	per 1000 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	0.528
1993	0.54
1994	0.554
1995	0.568
1996	0.591
1997	0.609
1998	0.626
1999	0.644
2000	0.664
2001	0.681
2004	0.774
2005	0.824
2007	0.8
2008	0.821
2009	0.838
2010	0.852
2011	0.877
2014	0.806
2015	0.978