Year	per 1,000 people
1960	3.775310754776
1970	2.97410011291504
1975	3.38170003890991
1985	3.35330009460449
1990	2.5
1993	2.7000000477
1996	2.2100000381
2002	2.5
2004	2.4
2005	2.2
2006	2.3
2007	2.3
2008	2.3
2009	2.3
2010	2.3
2011	2.27
2012	2.33
2013	2.3
2014	2.24
2015	2.29
2016	2.25