Year	Percent
1982	28.02
1996	30.7
2005	30.35
2006	31.69
2007	32.05
2008	32.25
2009	31.78
2010	32.2
2011	32.99
2012	33.65
2013	34.28
2014	33.76
2015	32.53
2016	31.88
2017	32.03