Year	Percent
1991	82.11
1992	83.021
1993	82.676
1994	82.779
1995	82.308
1996	81.927
1997	81.872
1998	79.533
1999	78.9
2000	79.408
2001	79.88
2002	80.211
2003	80.131
2004	80.411
2005	80.282
2006	80.27
2007	80.446
2008	80.364
2009	80.178
2010	80.297
2011	80.456
2012	80.379
2013	79.626
2014	78.854
2015	77.298
2016	76.772
2017	76.453
2018	76.107
2019	75.767
2020	75.573
2021	75.338
2022	75.07