Year	Percent
1991	79.522
1992	79.457
1993	79.314
1994	79.277
1995	79.23
1996	79.222
1997	79.206
1998	79.152
1999	79.112
2000	79.085
2001	79.081
2002	79.087
2003	79.115
2004	79.16
2005	79.216
2006	79.309
2007	78.535
2008	77.699
2009	76.794
2010	75.816
2011	74.746
2012	74.81
2013	74.858
2014	74.893
2015	74.903
2016	74.889
2017	74.643
2018	74.389
2019	74.13
2020	73.869
2021	73.602
2022	73.336