Year	per 1000 people
1960	0.396
1965	0.335
1970	0.348
1975	0.351
1977	0.637
1984	1.244
1990	0.958
1991	1.167
1992	1.201
1993	1.109
1994	1.275
1995	1.247
1996	1.317
1997	1.33
1998	1.317
1999	1.377
2000	1.452
2001	1.551
2002	1.575
2003	1.506
2009	1.607
2010	1.687
2011	1.665