| Year | Value | | 2021 | 27,716 | | 2020 | 27,872 | | 2019 | 28,157 | | 2018 | 28,241 | | 2017 | 29,248.142 | | 2016 | 29,236.65 | | 2015 | 28,866 | | 2013 | 29,979 | | 2012 | 29,406 | | 2011 | 30,071 | | 2010 | 29,929 | | 2009 | 33,698 | | 2008 | 29,959 | | 2007 | 29,976 | | 2006 | 29,620 | | 2005 | 28,470 | | 2004 | 29,304 | | 2003 | 29,327 | | 2002 | 29,410 | | 2001 | 29,503 | | 2000 | 29,330 | | 1999 | 29,171 | | 1998 | 31,793 | | 1997 | 31,879 | | 1996 | 31,910 | | 1995 | 31,997 |
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