Year	Percent
1991	80.934
1992	80.399
1993	80.692
1994	81.314
1995	82.742
1996	78.714
1997	81.556
1998	81.548
1999	78.344
2000	79.511
2001	79.549
2002	78.569
2003	80.31
2004	80.783
2005	81.992
2006	81.556
2007	82.361
2008	82.726
2009	81.507
2010	80.685
2011	79.812
2012	81.476
2013	80.18
2014	79.552
2015	79.298
2016	80.396
2017	80.483
2018	80.423
2019	80.363
2020	80.369
2021	80.34
2022	80.296