Year	per 1,000 people
1960	1.84541928768158
1970	2.32170009613037
1975	2.05879998207092
1990	1.317800045
1991	1.4110000134
1993	1.3999999762
1996	1.6699999571
2003	1
2004	1
2006	1.1
2007	1.1
2008	1.1
2009	1.1
2011	1.07
2012	1.1
2013	1.12
2014	1.15
2015	1.13
2016	1.27
2017	1.29