Year	Percent
1991	26.374
1992	25.933
1993	25.64
1994	24.982
1995	36.575
1996	36.176
1997	35.409
1998	36.453
1999	36.095
2000	35.925
2001	35.587
2002	35.492
2003	34.837
2004	34.567
2005	34.414
2006	33.909
2007	33.684
2008	29.988
2009	30.112
2010	31.565
2011	28.735
2012	28.405
2013	28.211
2014	27.919
2015	27.805
2016	27.62
2017	27.35
2018	27.313
2019	27.272
2020	27.228
2021	27.179
2022	27.131