Year	Percent
1991	75.186
1992	75.428
1993	75.091
1994	74.699
1995	75.621
1996	75.489
1997	74.984
1998	74.727
1999	74.705
2000	74.326
2001	74.061
2002	75.023
2003	74.701
2004	74.307
2005	73.879
2006	73.316
2007	72.609
2008	72.103
2009	71.693
2010	71.204
2011	70.413
2012	70.172
2013	69.629
2014	69.251
2015	68.944
2016	68.699
2017	68.648
2018	68.567
2019	68.483
2020	68.395
2021	68.309
2022	68.221