Year	Percent
1999	10.65302
2000	10.57629
2001	10.39337
2002	9.83249
2004	12.74032
2005	15.2609
2007	17.00127
2008	18.22036
2009	19.75587
2010	20.6138
2011	20.24881
2012	20.7934
2013	19.79739
2014	19.58983