Year	Percent
1991	40.376
1992	37.814
1993	50.934
1994	53.737
1995	54.647
1996	52.509
1997	49.956
1998	53.782
1999	51.475
2000	51.551
2001	52.423
2002	52.186
2003	50.045
2004	48.437
2005	47.056
2006	45.603
2007	43.903
2008	45.323
2009	45.748
2010	47.284
2011	45.619
2012	44.075
2013	44.708
2014	40.579
2015	40.088
2016	38.343
2017	38.965
2018	37.744
2019	37.13
2020	36.44
2021	35.781
2022	35.2