Year	Percent
1991	45.972
1992	38.513
1993	32.277
1994	27.983
1995	23.095
1996	22.609
1997	33.406
1998	34.989
1999	37.268
2000	40.104
2001	38.795
2002	38.62
2003	33.672
2004	35.88
2005	34.96
2006	41.659
2007	38.477
2008	39.871
2009	35.401
2010	37.225
2011	39.283
2012	36.41
2013	37.752
2014	38.863
2015	38.654
2016	37.994
2017	38.93
2018	39.478
2019	40.057
2020	40.651
2021	41.357
2022	42.027