Year	Percent
1991	56.942
1992	53.842
1993	49.759
1994	45.759
1995	45.656
1996	47.141
1997	49.574
1998	52.313
1999	51.887
2000	48.401
2001	48.955
2002	53.663
2003	56.291
2004	57.256
2005	59.162
2006	62.153
2007	60.855
2008	57.981
2009	61.37
2010	63.992
2011	64.056
2012	63.919
2013	63.071
2014	65.187
2015	66.795
2016	67.534
2017	67.133
2018	67.401
2019	67.939
2020	68.36
2021	68.864
2022	69.373