Year	Percent
1991	78.394
1992	77.917
1993	77.594
1994	77.304
1995	77.092
1996	76.739
1997	76.513
1998	76.329
1999	76.186
2000	76.097
2001	75.192
2002	74.655
2003	74.311
2004	74.143
2005	74.043
2006	73.414
2007	72.945
2008	72.603
2009	72.405
2010	72.269
2011	72.23
2012	72.142
2013	71.986
2014	71.013
2015	70.724
2016	70.277
2017	70.012
2018	69.819
2019	69.854
2020	70.074
2021	70.261
2022	70.339