Year	Percent
1986	20.4
1987	16.97
1992	15.4
1996	18.7
2001	27.59
2002	26.95
2003	25.29
2004	25.02
2005	22.6
2006	22.66
2007	20.8
2008	21.39
2009	22.28
2010	21.9
2011	20.5
2012	19.3
2013	18.22
2014	17.64
2015	16.64
2016	17.5
2017	17.8
2018	18.52
2019	19.95
2020	25.8