Year	Percent
1991	39.969
1992	37.165
1993	35.681
1994	36.774
1995	39.38
1996	38.949
1997	41.902
1998	47.071
1999	50.451
2000	52.939
2001	51.608
2002	48.482
2003	48.749
2004	48.603
2005	51.726
2006	53.941
2007	52.872
2008	46.429
2009	34.638
2010	30.017
2011	28.394
2012	26.978
2013	29.408
2014	29.6
2015	30.522
2016	33.831
2017	34.788
2018	34.675
2019	34.139
2020	33.817
2021	33.613
2022	33.462