Year	Percent
1998	25
1999	25.37
2000	29.88
2001	30.69
2002	33.29
2003	32.31
2004	29.45
2005	29.12
2006	28.34
2007	26.54
2008	22.41
2009	23.52
2010	24.68
2011	24.64
2012	24.73
2013	24.56
2014	24.89
2015	25.15
2016	26.54
2017	27.04
2018	26.91
2019	28.47
2020	29.22