Year	Percent
1991	69.72668
1992	69.74481
1993	70.03774
1994	69.71031
1995	69.99045
1996	69.98012
1997	69.68861
1998	69.21493
1999	69.22856
2000	68.6657
2001	69.06095
2002	69.66083
2003	68.96731
2004	68.67221
2005	67.95092
2006	67.10835
2007	66.07261
2008	64.20851
2009	60.54508
2010	63.83107
2011	64.09782
2012	63.80126
2013	62.87837
2014	62.41761
2015	60.61647
2016	59.41687
2017	58.56618
2018	57.64448
2019	56.78312