Year | Value | 2021 | 26.048045610423 | 2020 | 26.237825174179 | 2019 | 26.42621782664 | 2018 | 26.616661291704 | 2017 | 26.80349644959 | 2016 | 26.992311792688 | 2015 | 27.18485613479 | 2014 | 27.377370316809 | 2013 | 27.569749652647 | 2012 | 27.762045143398 | 2011 | 28.125165245081 | 2010 | 28.319218604109 | 2009 | 28.471908144003 | 2008 | 28.623724478403 | 2007 | 28.775157685805 | 2006 | 28.927078272872 | 2005 | 29.079008547819 | 2004 | 29.230771677792 | 2003 | 29.596827891836 | 2002 | 29.749719177841 | 2001 | 29.902610463846 | 2000 | 30.05550174985 | 1999 | 30.196761368088 | 1998 | 30.337498328721 | 1997 | 30.478235289354 | 1996 | 30.618972249986 | 1995 | 30.759709205651 | 1994 | 30.900446166284 | 1993 | 31.030509586801 | 1992 | 31.171198154897 | 1991 | 31.311886722993 | 1990 | 31.452575291089 |
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