Year	Percent
1991	57.639
1992	57.397
1993	56.822
1994	57.563
1995	56.862
1996	57.536
1997	58.584
1998	60.608
1999	62.091
2000	63.075
2001	64.12
2002	65.075
2003	65.115
2004	65.533
2005	66.01
2006	66.107
2007	65.694
2008	66.339
2009	67.839
2010	68.01
2011	68.45
2012	71.551
2013	72.041
2014	72.04
2015	72.328
2016	72.709
2017	72.788
2018	72.915
2019	73.11
2020	73.311
2021	73.473
2022	73.607