Year	Percent
1999	4.24
2000	4.82
2001	5.07
2002	6.33
2006	8.66
2007	9.53
2008	8.85
2009	11.15
2011	15.27
2012	16.76
2013	16.16
2014	17.12
2015	17.85
2016	18.61