Year	Percent
1991	34.942
1992	32.458
1993	34.455
1994	36.213
1995	35.856
1996	36.312
1997	35.873
1998	36.109
1999	37.173
2000	41.493
2001	41.136
2002	40.89
2003	41.998
2004	47.204
2005	46.003
2006	45.282
2007	48.078
2008	47.744
2009	48.496
2010	48.326
2011	48.291
2012	49.456
2013	48.821
2014	48.417
2015	47.367
2016	49.11
2017	49.67
2018	50.086
2019	50.496
2020	50.922
2021	51.285
2022	51.619