Year	Percent
1991	56.33435
1992	57.26305
1993	59.11538
1994	59.07414
1995	59.8546
1996	60.78912
1997	61.15709
1998	61.28449
1999	61.48139
2000	61.37464
2001	62.1162
2002	63.03577
2003	63.11448
2004	63.05555
2005	63.20267
2006	62.50505
2007	61.76371
2008	62.1138
2009	64.10677
2010	62.19673
2011	61.62967
2012	61.56544
2013	62.00043
2014	61.92817
2015	61.98958
2016	62.05394
2017	61.89698