Year	Percent
1991	75.037
1992	74.75
1993	74.69
1994	75.29
1995	75.971
1996	75.948
1997	75.694
1998	75.342
1999	76.154
2000	76.06
2001	76.131
2002	76.223
2003	76.534
2004	77.293
2005	77.499
2006	76.157
2007	75.607
2008	76.682
2009	76.808
2010	77.227
2011	75.734
2012	75.487
2013	75.043
2014	74.024
2015	74.074
2016	72.953
2017	72.963
2018	72.932
2019	72.899
2020	72.863
2021	72.826
2022	72.786