Year	% of population
1995	67.6
1996	66.6
1997	65.9
1998	65.1
1999	64.4
2000	63.7
2001	62.7
2002	63
2003	61.8
2004	59.6
2005	58.5
2006	57.7
2007	56.9
2008	55.4
2009	55.6
2010	54.1
2011	53.2
2012	52.3
2013	51.8
2014	51.5
2015	52.2
2016	52.6
2017	52.7