Year Ratio 1996-01-01 2.27381992340088 1997-01-01 2.22949004173279 1998-01-01 2.14242005348206 1999-01-01 1.85774004459381 2000-01-01 1.78630995750427 2001-01-01 1.75762999057770 2002-01-01 1.78083002567291 2003-01-01 1.73133003711700 2004-01-01 1.68506002426147 2005-01-01 1.65288996696472 2006-01-01 1.59156000614166 2007-01-01 1.56484997272491 2008-01-01 1.57823002338409 2009-01-01 1.55373001098633 2010-01-01 1.53515005111694 2011-01-01 1.48919999599457 2012-01-01 1.44228994846344 2013-01-01 1.42316997051239 2014-01-01 1.43516004085541 2015-01-01 1.38268995285034 2016-01-01 1.39269995689392