Year Number 1996 0.310659021139145 1998 0.382473677396774 2000 0.467802941799164 2002 0.321516633033752 2003 0.218241095542908 2004 0.126583278179169 2005 -0.0982957854866982 2006 -0.739193975925446 2007 -0.562502324581146 2008 -0.529666900634766 2009 -0.455878525972366 2010 -0.495821505784988 2011 -0.405181705951691 2012 -0.32114115357399 2013 -0.42992576956749 2014 -0.874775230884552 2015 -0.969098031520844 2016 -1.02308261394501 2017 -1.04549336433411 2018 -1.01793563365936 2019 -0.846735775470734 2020 -0.810611665248871 2021 -0.789982855319977 2022 -0.622607707977295