Year	per 1,000 people
1960	3.20179533958435
1970	3.69180011749268
1975	4.9951000213623
1987	3.56030011177063
1990	3.3452999592
1993	3.5
1996	3.1099998951
2000	2.82
2001	2.78
2002	2.59
2003	2.42
2005	2.52
2006	2.48
2007	2.47
2008	2.44
2009	2.43
2010	2.37
2011	2.31
2012	2.27
2013	2.25
2014	2.22
2015	2.15
2016	2.11
2017	2.09