Year	Percent
1991	69.87049
1992	69.65722
1993	69.47933
1994	69.23437
1995	68.96197
1996	68.56263
1997	68.24855
1998	67.94112
1999	67.47514
2000	66.797
2001	66.07192
2002	65.29991
2003	64.68284
2004	64.0005
2005	63.31273
2006	62.79823
2007	62.23494
2008	61.7301
2009	60.77958
2010	59.59992
2011	60.15
2012	58.34909
2013	56.33991
2014	56.64988
2015	57.99724
2016	57.22755
2017	56.53
2018	56.13307
2019	55.7918