Year	per 1,000 people
1960	0.55726158618927
1970	0.520799994468689
1975	0.526300013065338
1980	0.573099970817566
1981	0.5692999958992
1986	0.599500000476837
1989	0.604300022125244
1990	0.6399999857
1991	0.6521999836
1992	0.6446999907
1993	0.6514999866
2000	0.67
2001	0.66
2002	0.69
2003	0.68
2004	0.68
2005	0.7
2007	1
2008	0.6
2009	0.6
2010	0.6
2011	0.6
2012	0.6
2013	0.6
2014	0.6
2015	0.6
2016	0.63
2017	0.63