Year	Percent
1991	79.758
1992	78.28
1993	77.712
1994	76.555
1995	76.833
1996	76.196
1997	75.059
1998	75.877
1999	75.917
2000	75.877
2001	75.918
2002	74.499
2003	73.676
2004	72.817
2005	72.114
2006	72.795
2007	73.532
2008	73.265
2009	72.391
2010	70.975
2011	71.586
2012	71.209
2013	70.692
2014	70.646
2015	70.736
2016	70.824
2017	70.755
2018	70.508
2019	70.313
2020	70.035
2021	69.676
2022	69.275