Year	Percent
1991	56.891
1992	59.18
1993	61.232
1994	62.907
1995	63.82
1996	64.865
1997	66.363
1998	66.833
1999	68.061
2000	68.978
2001	68.252
2002	68.696
2003	69.798
2004	70.345
2005	70.691
2006	70.184
2007	70.659
2008	70.958
2009	73.716
2010	74.881
2011	74.235
2012	74.738
2013	75.02
2014	74.766
2015	74.615
2016	74.134
2017	74.393
2018	75.007
2019	75.475
2020	75.824
2021	76.157
2022	76.483