Year	Percent
1999	17.98051
2000	15.78743
2004	19.20321
2005	20.47607
2006	20.64517
2008	22.00287
2009	23.49593
2010	26.07926
2012	23.0469
2013	21.71157
2014	23.62065
2015	25.67661