Year	Percent
1999	21.42
2000	23.02
2001	24.38
2002	25.18
2006	29.66
2007	25.51
2008	24.07
2009	23.51
2011	23.95
2012	19.95
2013	21
2014	21.28
2015	19.69
2016	17.38