Year	Percent
1991	55.263
1992	53.942
1993	59.215
1994	58.61
1995	61.115
1996	64.611
1997	63.772
1998	65.93
1999	66.236
2000	66.769
2001	66.979
2002	68.333
2003	68.399
2004	70.271
2005	72.254
2006	72.512
2007	72.007
2008	75.788
2009	78.713
2010	78.786
2011	78.108
2012	78.818
2013	79.797
2014	81.78
2015	79.589
2016	80.577
2017	80.792
2018	81.075
2019	81.365
2020	81.628
2021	81.912
2022	82.108