Year	Percent
1991	36.094
1992	38.335
1993	39.488
1994	39.66
1995	39.591
1996	37.688
1997	36.326
1998	33.849
1999	33.563
2000	32.163
2001	31.891
2002	34.052
2003	33.829
2004	37.324
2005	38.753
2006	38.839
2007	39.565
2008	39.918
2009	37.847
2010	37.647
2011	38.385
2012	38.272
2013	36.272
2014	33.487
2015	31.12
2016	30.809
2017	29.595
2018	29.603
2019	29.393
2020	28.963
2021	28.372
2022	27.627