Year	Percent
1991	20.354
1992	21.797
1993	23.052
1994	22.186
1995	21.121
1996	21.911
1997	20.715
1998	20.057
1999	19.279
2000	18.328
2001	21.099
2002	23.497
2003	26.454
2004	30.352
2005	33.565
2006	37.612
2007	42.348
2008	46.544
2009	51.125
2010	56.67
2011	58.105
2012	59.077
2013	59.665
2014	59.997
2015	61.808
2016	61.942
2017	61.797
2018	61.94
2019	62.321
2020	62.642
2021	62.961
2022	63.323