Year	Percent
1991	78.397
1992	78.566
1993	78.856
1994	79.229
1995	79.492
1996	78.013
1997	76.515
1998	75.454
1999	74.938
2000	74.449
2001	74.265
2002	74.448
2003	74.774
2004	74.861
2005	74.896
2006	74.483
2007	74.756
2008	75.447
2009	76.86
2010	78.59
2011	80.076
2012	81.359
2013	82.92
2014	84.495
2015	85.734
2016	85.69
2017	85.706
2018	86.041
2019	86.594
2020	87.182
2021	86.616
2022	85.998