Year	per 1000 people
1960	0.45
1970	0.429
1980	1.087
1985	1.219
1991	1.315
1993	0.11
1997	1
2000	1.017
2001	1.068
2002	1.092
2003	1.071
2004	0.994
2005	1.07
2006	1.033
2007	1.025
2008	0.989
2009	0.96
2010	0.934
2011	0.925
2012	0.933
2013	0.929
2014	0.939
2015	0.922