Year | Value | 2021 | 17.452982267598 | 2020 | 17.689414293391 | 2019 | 17.925846319183 | 2018 | 18.162278344976 | 2017 | 18.393336915637 | 2016 | 18.629768941429 | 2015 | 18.866200967222 | 2014 | 19.101558301988 | 2013 | 19.336915636754 | 2012 | 19.572272971521 | 2011 | 19.807630306287 | 2010 | 20.042987641053 | 2009 | 20.27834497582 | 2008 | 20.513702310586 | 2007 | 20.749059645352 | 2006 | 20.984416980118 | 2005 | 21.219774314884 | 2004 | 21.455131649651 | 2003 | 21.690488984417 | 2002 | 21.925846319183 | 2001 | 22.161203653949 | 2000 | 22.396560988716 | 1999 | 22.631918323482 | 1998 | 22.867275658248 | 1997 | 23.102632993014 | 1996 | 23.337990327781 | 1995 | 23.573347662547 | 1994 | 23.808704997313 | 1993 | 24.044062332079 | 1992 | 24.279419666846 | 1991 | 24.514777001612 | 1990 | 24.750134336378 |
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