Year	Percent
1991	76.241
1992	76.316
1993	75.894
1994	75.748
1995	75.833
1996	75.204
1997	74.282
1998	73.266
1999	72.225
2000	71.348
2001	70.714
2002	70.128
2003	69.824
2004	71.495
2005	71.026
2006	69.047
2007	67.084
2008	67.497
2009	68.196
2010	68.63
2011	69.109
2012	69.628
2013	70.951
2014	72.244
2015	71.976
2016	71.772
2017	71.587
2018	71.45
2019	71.253
2020	71.008
2021	70.746
2022	70.451