Year	Percent
1999	22.45
2000	25.06
2001	25.86
2002	28.13
2006	33.99
2007	29.94
2008	29.34
2009	29.95
2011	29.93
2012	28.66
2013	29.43
2014	30.2
2015	28.49
2016	24.19
2018	28.82
2020	27.18