Year	Percent
1991	77.682
1992	77.91
1993	78.159
1994	78.404
1995	78.658
1996	78.596
1997	79.026
1998	79.488
1999	80.293
2000	80.097
2001	79.876
2002	79.655
2003	79.42
2004	79.182
2005	78.937
2006	78.687
2007	78.427
2008	78.115
2009	78.157
2010	78.222
2011	78.542
2012	78.863
2013	79.145
2014	79.824
2015	80.133
2016	80.649
2017	80.845
2018	80.851
2019	80.866
2020	80.89
2021	80.919
2022	80.959