Year	Percent
1991	30.605
1992	36.629
1993	36.589
1994	35.835
1995	38.793
1996	37.324
1997	40.414
1998	42.037
1999	44.158
2000	46.098
2001	46.094
2002	39.778
2003	39.546
2004	34.631
2005	35.411
2006	33.881
2007	33.76
2008	32.595
2009	32.802
2010	35.182
2011	33.212
2012	33.376
2013	32.834
2014	32.097
2015	28.982
2016	26.613
2017	27.334
2018	27
2019	26.814
2020	26.667
2021	26.659
2022	26.646