Year Percent 1998-01-01 4.82697388994681 1999-01-01 4.69082429074762 2000-01-01 4.37386476974954 2001-01-01 3.95683977724728 2002-01-01 3.76535650462514 2003-01-01 3.64814758149451 2004-01-01 3.41312175280228 2005-01-01 3.25205595066279 2006-01-01 2.86389652341300 2007-01-01 2.55770556684042 2008-01-01 2.85143669679632 2009-01-01 3.25477704066217 2010-01-01 3.50107650086228 2011-01-01 3.49373446508289 2012-01-01 4.53377726038141 2013-01-01 5.13065776932579