Year	Percent
1992	22.36
1995	20.92
1996	20.19
1997	17.4
1998	16.79
1999	17.3
2000	17.81
2001	17.64
2002	22.22
2003	19.52
2004	22.33
2005	20.25
2006	21.44
2007	20.14
2008	18.6
2009	20.75
2010	22.11
2011	23.91
2012	22.56
2013	23.73
2014	24.02
2015	21.66
2016	20.6
2017	18.32
2018	16.24
2019	16.76
2020	17.34