Year	Percent
1991	51.814
1992	61.096
1993	63.705
1994	63.788
1995	65.015
1996	65.149
1997	66.268
1998	67.355
1999	69.196
2000	70.526
2001	70.727
2002	69.67
2003	70.673
2004	70.862
2005	72.128
2006	72.829
2007	73.455
2008	73.398
2009	75.778
2010	77.134
2011	77.202
2012	77.402
2013	79.093
2014	78.347
2015	77.92
2016	77.419
2017	77.48
2018	77.845
2019	78.244
2020	78.557
2021	78.878
2022	79.206