Year	per 1000 people
1960	0.143
1965	0.161
1970	0.232
1975	0.234
1980	0.255
1981	0.255
1985	0.315
1986	0.335
1987	0.348
1988	0.367
1989	0.374
1990	0.392
1991	0.393
1992	0.411
1993	0.431
1994	0.449
1995	0.478
1996	0.496
1997	0.658
1999	0.683
2000	0.689
2002	0.697
2008	0.923
2010	1.173
2011	1.281
2015	1.533