Year	Percent
1991	68.58796
1992	68.52644
1993	68.42493
1994	68.25794
1995	68.10058
1996	67.76572
1997	67.43736
1998	67.98289
1999	67.91278
2000	67.67382
2001	67.50151
2002	67.45809
2003	67.30925
2004	67.04148
2005	66.685
2006	66.40027
2007	66.06871
2008	65.68176
2009	65.31032
2010	64.86414
2011	64.21582
2012	64.08657
2013	63.67192
2014	63.38945
2015	62.8178
2016	62.17875
2017	61.56705
2018	61.05437
2019	60.48027