Year Percent 2003-01-01 6.280992985 2004-01-01 10.383783340 2005-01-01 14.681278230 2006-01-01 18.260509490 2007-01-01 21.457113270 2008-01-01 26.729616170 2009-01-01 30.450315480 2010-01-01 31.502517700 2011-01-01 32.755725860