Year	per 1,000 people
1980	1.033
1981	1.089
1982	1.17
1983	1.207
1984	1.28
1985	1.362
1986	1.419
1987	1.485
1990	1.565
1991	1.561
2000	1.306
2001	1.298
2002	1.296
2003	1.329
2004	1.371
2005	1.41
2006	1.462
2007	1.543
2008	1.591
2009	1.674
2010	1.749
2011	1.838
2012	1.912
2013	1.993
2014	2.08
2015	2.103