Year	Percent
1991	31.11
1992	32.075
1993	31.902
1994	28.723
1995	28.616
1996	27.355
1997	29.546
1998	30.75
1999	28.116
2000	28.554
2001	27.965
2002	25.931
2003	24.748
2004	25.77
2005	26.905
2006	29.901
2007	30.541
2008	30.706
2009	32.101
2010	31.218
2011	31.204
2012	30.404
2013	28.718
2014	28.686
2015	30.976
2016	30.18
2017	29.776
2018	30.057
2019	30.212
2020	30.453
2021	30.419
2022	30.478