Year	per 1000 people
1960	0.276
1965	0.481
1970	0.739
1971	0.911
1972	0.845
1977	1.036
1980	1.367
1983	1.415
1984	1.407
1985	1.406
1989	1.403
1990	1.374
1991	1.47
1992	1.65
1993	1.425
1995	1.306
1996	1.354
1997	1.295
1998	1.289
1999	1.282
2000	1.389
2002	1.305
2007	1.146
2009	1.144
2010	1.254
2011	1.24
2012	1.283
2013	1.286