Year	Percent
1998	19.4144
1999	20.16816
2000	20.71592
2001	20.87829
2002	21.39928
2003	21.84748
2004	21.62114
2005	21.24898
2006	21.0036
2007	20.91213
2008	20.86586
2010	22.9172
2011	22.63818
2012	22.82339
2013	22.97133
2014	22.54562