| Year | Value | | 2022 | 3.0434433469848 | | 2021 | 1.7156427545126 | | 2020 | 1.7953714708311 | | 2019 | 2.2060730578152 | | 2018 | 1.1527789637552 | | 2017 | 0.45006382328555 | | 2016 | 3.1905617972377 | | 2015 | 3.1690979675083 | | 2014 | 0.9121395454501 | | 2013 | 4.6316161972946 | | 2012 | 5.0101877313447 | | 2011 | 1.759587042738 | | 2010 | 0.39152501122761 | | 2009 | 4.4150037479522 | | 2008 | 4.9587509202315 | | 2007 | 2.654646450607 | | 2006 | 6.537843952996 | | 2005 | 3.0944901145618 | | 2004 | 2.429766079618 | | 2003 | 0.63184498736316 | | 2002 | 4.3787597178087 | | 2001 | 0.055989921814058 | | 2000 | 0.88199151702543 | | 1999 | 4.1426713728405 | | 1996 | 10.03112033195 | | 1995 | 9.4180074345223 | | 1994 | 42.439675033345 | | 1993 | 4.9236641221374 | | 1992 | -3.9354681007088 | | 1991 | -1.6783496895654 | | 1990 | 2.8890537421695 | | 1989 | -1.7969888295289 | | 1988 | 1.0304219823355 | | 1987 | 0.44356826022684 | | 1986 | 4.1581108829568 |
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