Year	Percent
1991	27.551
1992	28.086
1993	27.113
1994	27.919
1995	28.835
1996	29.272
1997	30.195
1998	29.926
1999	30.287
2000	28.669
2001	26.793
2002	25.076
2003	21.263
2004	19.207
2005	18.908
2006	18.15
2007	17.89
2008	17.625
2009	20.033
2010	21.991
2011	24.83
2012	25.686
2013	25.58
2014	24.66
2015	24.804
2016	24.418
2017	23.529
2018	23.418
2019	23.433
2020	23.402
2021	23.464
2022	23.481