Year	Percent
1991	68.434
1992	71.257
1993	73.257
1994	72.291
1995	72.93
1996	72.196
1997	72.314
1998	72.718
1999	73.836
2000	71.998
2001	70.982
2002	71.66
2003	72.165
2004	73.638
2005	74.493
2006	74.883
2007	76.628
2008	79.088
2009	78.831
2010	78.246
2011	77.807
2012	78.937
2013	79.292
2014	78.105
2015	78.29
2016	78.335
2017	78.281
2018	78.24
2019	78.202
2020	78.148
2021	78.089
2022	78.026