Year Percent 2003-01-01 17.79322433 2004-01-01 20.10606194 2005-01-01 24.50034523 2006-01-01 26.38514137 2007-01-01 27.20348930 2008-01-01 30.83038902 2009-01-01 33.67389297 2010-01-01 35.78578186 2011-01-01 37.73188019