Year	per 1000 people
1960	0.946
1965	0.876
1970	0.822
1981	1.388
1984	1.886
1988	3
1990	3.656
1991	3.998
1992	4.365
1993	4.727
1994	4.981
1995	5.211
1996	5.489
1997	5.693
1998	5.749
1999	5.854
2000	5.937
2001	5.948
2002	5.997
2003	6.065
2004	6.202
2005	6.269
2006	6.34
2007	6.418
2008	6.603
2009	6.628
2010	6.766
2011	6.943
2012	7.235
2013	7.366
2014	7.519