Year	Percent
1991	63.791
1992	65.565
1993	70.821
1994	76.204
1995	74.5
1996	73.256
1997	74.84
1998	76.321
1999	77.745
2000	79.19
2001	80.784
2002	77.654
2003	74.559
2004	75.056
2005	74.64
2006	74.006
2007	72.848
2008	72.32
2009	70.043
2010	68.462
2011	67.915
2012	66.658
2013	66.413
2014	66.636
2015	67.07
2016	67.248
2017	67.332
2018	67.313
2019	67.283
2020	67.251
2021	67.199
2022	67.145