Year	Percent
1991	73.284
1992	73.766
1993	73.835
1994	73.746
1995	73.369
1996	72.17
1997	71.225
1998	70.673
1999	70.494
2000	72.736
2001	71.959
2002	71.235
2003	70.902
2004	70.686
2005	70.532
2006	70.013
2007	70.558
2008	70.994
2009	70.955
2010	71.813
2011	72.824
2012	74.922
2013	76.231
2014	76.662
2015	77.204
2016	77.291
2017	77.48
2018	77.745
2019	78.036
2020	78.313
2021	77.835
2022	77.35