Year	Percent
1991	28.86
1992	26.765
1993	26.562
1994	28.542
1995	29.617
1996	30.162
1997	29.471
1998	29.655
1999	27.885
2000	27.478
2001	29.22
2002	29.162
2003	28.7
2004	28.087
2005	27.284
2006	26.036
2007	26.492
2008	25.85
2009	26.354
2010	25.603
2011	25.45
2012	26.219
2013	26.171
2014	24.362
2015	22.725
2016	21.938
2017	21.819
2018	21.616
2019	21.459
2020	21.336
2021	21.225
2022	21.135