Year	Percent
1991	33.769
1992	32.686
1993	29.871
1994	29.406
1995	28.791
1996	29.596
1997	28.931
1998	29.647
1999	27.745
2000	33.756
2001	31.546
2002	30.941
2003	30.057
2004	30.023
2005	29.995
2006	30.911
2007	30.566
2008	30.17
2009	27.597
2010	27.225
2011	27.415
2012	27.436
2013	25.066
2014	24.408
2015	25.069
2016	24.226
2017	24.5
2018	24.783
2019	24.502
2020	24.177
2021	23.839
2022	23.514