Year	per 1,000 people
1960	0.774723947048187
1970	1.1813999414444
1981	1.45819997787476
1990	2.4964001179
1997	2.2999999523
2000	2.3
2002	2.24
2003	2.24
2004	2.24
2005	2.25
2006	2.3
2007	2.2
2008	2.21
2009	2.17
2010	2.2
2011	2.14
2012	2.09
2013	2.2
2014	2.65
2015	2.2
2016	2.23
2017	2.24