Year	Percent
1991	55.713
1992	56.739
1993	54.253
1994	56.215
1995	57.389
1996	58.95
1997	60.441
1998	61.052
1999	62.589
2000	63.827
2001	66.024
2002	65.523
2003	64.066
2004	66.762
2005	67.733
2006	69.198
2007	71.656
2008	75.114
2009	75.674
2010	76.899
2011	77.145
2012	77.492
2013	77.712
2014	77.068
2015	76.907
2016	78.879
2017	79.174
2018	79.795
2019	80.416
2020	80.909
2021	81.417
2022	81.847