Year	Percent
1991	39.993
1992	39.099
1993	38.245
1994	40.103
1995	44.513
1996	45.769
1997	47.207
1998	47.892
1999	46.544
2000	50.175
2001	47.435
2002	47.075
2003	45.318
2004	45.295
2005	46.829
2006	47.519
2007	48.083
2008	47.078
2009	47.905
2010	48.784
2011	48.575
2012	50.517
2013	50.33
2014	52.331
2015	52.517
2016	53.108
2017	53.039
2018	53.359
2019	53.698
2020	54.107
2021	54.505
2022	54.885