Year	Percent
2000	32.71
2001	30.93
2002	31.53
2003	29.88
2004	29.45
2005	29.85
2006	28.34
2007	26.32
2008	25.56
2009	25.02
2010	25.52
2011	24.52
2012	22.26
2013	21.83
2014	20.94
2015	19.8
2016	19.78
2017	19.82