Year	per 1000 people
1961	1.1
1966	1.2
1971	1.2
1976	1.5
1981	1.8
1984	1.8
1985	1.9
1986	2
1987	2.1
1988	2.1
1989	2.1
1990	2.2
1991	2.3
1992	2.4
1993	2.4
1994	2.4
1995	2.4
1996	2.513
1997	2.4
1998	2.4
1999	2.4
2000	2.5
2001	2.479
2002	2.5
2006	2.672
2009	2.885
2011	3.287
2012	3.285
2013	3.371
2014	3.44
2015	3.496