Year	% (national estimate)
1980	49
1983	55.84
1986	56.77
1988	60.95
1990	57.3
2000	57.42
2001	55.8
2002	55.3
2004	56.9
2005	56.8
2006	58.2
2007	52.9
2009	56
2010	56.3
2011	54.3