Year Percent 1995-01-01 50.3427670425000 1996-01-01 50.0713751025000 1997-01-01 49.4095232325000 1998-01-01 48.8453692300000 1999-01-01 49.0202063875000 2000-01-01 49.5077626375000 2001-01-01 49.1892531450000 2002-01-01 48.5387801350000 2003-01-01 48.6285735225000 2004-01-01 49.2368936950000 2005-01-01 50.2395697025000 2006-01-01 50.9295660850000 2007-01-01 52.1535733775000 2008-01-01 53.0628154425000 2009-01-01 52.6240383200000 2010-01-01 53.5313517275000 2011-01-01 54.1583603775000 2012-01-01 59.2250000000000 2013-01-01 59.7500000000000 2014-01-01 60.4250000000000 2015-01-01 60.7333333333333 2016-01-01 61.0666666666667 2017-01-01 61.3083333333333