Year	per 1,000 people
1960	0.45
1970	0.429
1980	1.087
1985	1.219
1991	1.315
1997	1
2000	0.953
2001	1.016
2002	1.058
2003	1.048
2004	0.963
2005	1.029
2006	1.001
2007	1.011
2008	0.993
2009	0.974
2010	0.971
2011	0.997
2012	1.016
2013	0.994
2014	0.976
2015	0.932
2016	0.842