Year Number 1996 -0.0383590497076511 1998 0.0678859651088715 2000 0.28022488951683 2002 0.628807723522186 2003 0.558495879173279 2004 0.686754405498505 2005 0.43447408080101 2006 0.560829281806946 2007 0.60539698600769 2008 0.573651909828186 2009 0.612926959991455 2010 0.608463644981384 2011 0.623747110366821 2012 0.606891453266144 2013 0.642667889595032 2014 0.619112372398376 2015 0.586513638496399 2016 0.654191136360168 2017 0.681904494762421 2018 0.793498814105988 2019 0.685416102409363 2020 0.607223808765411 2021 0.621482789516449 2022 0.61216127872467