Year	per 1,000 people
1970	0.89
1971	0.919
1972	0.953
1973	1.012
1974	1.025
1975	1.121
1976	1.114
1977	1.158
1978	1.238
1979	1.311
1990	2.151
1991	2.203
1992	2.262
1993	2.185
1994	2.193
1995	2.27
1996	2.227
1997	2.241
1998	2.24
1999	2.179
2000	2.186
2001	2.172
2002	2.215
2003	2.148
2004	2.163
2005	2.113
2006	2.492
2007	2.425
2008	2.571
2009	2.567
2010	2.646
2011	2.694
2012	2.741
2013	2.761
2015	2.834