Year	per 1,000 people
1970	3.2
1971	3.3
1972	3.32
1973	3.4
1974	3.475
1975	3.63
1976	3.72
1977	3.81
1978	3.95
1979	4
1980	4.123
1981	4.212
1982	4.319
1983	4.333
1984	4.471
1985	4.611
1986	4.699
1987	4.808
1988	4.868
1989	4.971
1990	4.926
1991	4.898
1992	4.726
1993	5.003
1994	4.899
1995	4.792
1996	3.119
1997	3.707
1998	3.852
1999	3.927
2000	3.924
2001	3.852
2002	3.992
2003	4.037
2004	4.027
2005	4.056
2006	4.12
2007	4.163
2008	4.271
2009	4.511
2010	4.751
2011	4.806
2012	4.793
2013	4.828
2014	5.106
2015	5.341
2016	6.386
2017	6.515
2018	7.555
2019	7.503
2020	4.821
2021	5.405