Year	Percent
1991	77.911
1992	77.404
1993	77.421
1994	77.148
1995	76.965
1996	77.211
1997	77.622
1998	77.843
1999	78.196
2000	79.292
2001	79.954
2002	80.306
2003	80.173
2004	80.114
2005	79.995
2006	79.92
2007	79.757
2008	79.583
2009	79.994
2010	79.748
2011	79.203
2012	79.061
2013	78.973
2014	78.961
2015	78.844
2016	78.79
2017	78.754
2018	78.723
2019	78.685
2020	78.636
2021	78.598
2022	78.552