| Year | Value | | 2020 | 0.11061949349989 | | 2019 | 0.113813822666 | | 2018 | 0.12175672014348 | | 2017 | 0.12280195250192 | | 2016 | 0.13658748549715 | | 2015 | 0.14211378718899 | | 2014 | 0.14773124841741 | | 2013 | 0.14917971373389 | | 2012 | 0.15104452227864 | | 2011 | 0.15317265664803 | | 2010 | 0.15884868845912 | | 2009 | 0.16453984816816 | | 2008 | 0.15915631872071 | | 2007 | 0.16463672330774 | | 2006 | 0.17022994831648 | | 2005 | 0.17597445414044 | | 2004 | 0.18171536396134 | | 2003 | 0.20069666125161 | | 2002 | 0.20713805480331 | | 2001 | 0.21381607541193 | | 2000 | 0.22082572310105 | | 1999 | 0.22791653824173 | | 1998 | 0.23529308282316 | | 1997 | 0.24291505328694 | | 1996 | 0.25085613447577 | | 1995 | 0.25951246581469 | | 1994 | 0.12539977448105 | | 1993 | 0.1295716439195 | | 1992 | 0.13381929363754 | | 1991 | 0.13818258396457 |
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