Year	per 1000 people
1960	0.891
1970	1.072
1971	1.026
1975	1.276
1981	1.172
1982	1.266
1984	1.38
1987	2.032
1988	2.015
1989	1.973
1990	2.259
1991	2.446
1992	2.422
1993	2.453
1997	2.465
1998	2.607
1999	2.591
2000	2.654
2001	2.926
2003	3.183
2006	3.88
2007	3.351
2009	3.073
2010	3.104
2011	3.185
2012	3.323
2013	3.518
2014	3.749
2015	3.908