Year	Percent
1991	72.34274
1992	72.25903
1993	72.04177
1994	71.84673
1995	71.47841
1996	71.13229
1997	70.87585
1998	70.60444
1999	70.17355
2000	69.9493
2001	69.60625
2002	69.08344
2003	68.69999
2004	68.51236
2005	68.34151
2006	67.92042
2007	67.60385
2008	67.26145
2009	67.06019
2010	66.84634
2011	66.4471
2012	66.1357
2013	71.91722
2014	72.39299
2015	72.26015
2016	72.41096
2017	72.67451
2018	72.45097
2019	72.14125