Year	Percent
1991	76.592
1992	76.623
1993	76.665
1994	76.519
1995	76.164
1996	75.933
1997	75.875
1998	75.791
1999	75.7
2000	75.599
2001	75.571
2002	76.158
2003	76.742
2004	77.31
2005	78.016
2006	78.695
2007	79.352
2008	79.139
2009	78.951
2010	78.58
2011	78.635
2012	78.674
2013	78.673
2014	78.627
2015	78.545
2016	78.497
2017	78.46
2018	78.409
2019	78.356
2020	78.301
2021	78.242
2022	78.178