Year Number 2004 -0.515539228916168 2005 -0.515336811542511 2006 -0.690099477767944 2007 -0.719671785831451 2008 -0.792954564094543 2009 -0.574568629264832 2010 -0.579521000385284 2011 -0.599480748176575 2012 -0.645014047622681 2013 -0.655830562114716 2014 -0.427611589431763 2015 -0.423639237880707 2016 -0.431269496679306 2017 -0.403690338134766 2018 -0.362755715847015 2019 -0.319078892469406 2020 -0.380405098199844 2021 -0.315788686275482 2022 -0.347820729017258