Year Ratio 1971-01-01 0.421880006790161 1972-01-01 0.428900003433228 1973-01-01 0.438210010528564 1975-01-01 0.461739987134933 1976-01-01 0.465229988098145 1977-01-01 0.471949994564056 1978-01-01 0.478949993848801 1980-01-01 0.487480014562607 1981-01-01 0.501609981060028 1982-01-01 0.497570008039474 1983-01-01 0.553780019283295 1984-01-01 0.515869975090027 1986-01-01 0.538330018520355 1987-01-01 0.543519973754883 1988-01-01 0.556169986724854 1989-01-01 0.570060014724731 1993-01-01 0.623610019683838 1994-01-01 0.639750003814697 1995-01-01 0.639119982719421 1996-01-01 0.644590020179749 1997-01-01 0.664969980716705 1999-01-01 0.699890017509460 2000-01-01 0.707480013370514 2001-01-01 0.714100003242493 2002-01-01 0.741659998893738 2003-01-01 0.803889989852905 2004-01-01 0.806710004806519 2005-01-01 0.823689997196198 2006-01-01 0.836239993572235 2007-01-01 0.862399995326996 2008-01-01 0.886759996414185 2009-01-01 0.922659993171692 2010-01-01 0.929250001907349 2011-01-01 0.944149971008301 2012-01-01 0.951979994773865 2013-01-01 1.009289979934690 2014-01-01 1.013339996337890 2015-01-01 1.012459993362430 2016-01-01 1.016589999198910