Year	Percent
1991	80.794
1992	81.008
1993	80.863
1994	81.159
1995	81.276
1996	81.447
1997	81.495
1998	80.992
1999	80.921
2000	80.668
2001	80.29
2002	79.924
2003	79.502
2004	79.031
2005	78.095
2006	78.02
2007	76.721
2008	76.652
2009	76.193
2010	75.413
2011	74.202
2012	73.535
2013	72.548
2014	70.858
2015	70.575
2016	70.267
2017	69.757
2018	69.019
2019	68.321
2020	67.568
2021	66.827
2022	66.11