Year	Percent
1991	71.88412
1992	72.09903
1993	71.90018
1994	71.77015
1995	71.85029
1996	71.57421
1997	71.60421
1998	71.29235
1999	71.19368
2000	70.64387
2001	70.95726
2002	69.67292
2003	69.01217
2004	68.46002
2005	68.14058
2006	67.67981
2007	66.81435
2008	65.98356
2009	65.19318
2010	64.15794
2011	62.96539
2012	61.17384
2013	59.16407
2014	57.64932
2015	58.06403
2016	57.03259
2017	56.13967
2018	55.35841
2019	54.47369