Year Number 1996 -0.1044110506773 1998 0.210070848464966 2000 0.454069554805756 2002 0.341267883777618 2003 0.473294764757156 2004 0.408443540334702 2005 0.185300454497337 2006 0.115620285272598 2007 0.243874251842499 2008 0.230824679136276 2009 0.349971473217011 2010 0.339617520570755 2011 0.391060173511505 2012 0.481707990169525 2013 0.416812211275101 2014 0.335749626159668 2015 0.253743559122086 2016 0.247532933950424 2017 0.225759148597717 2018 0.206865146756172 2019 0.0881585031747818 2020 0.174368306994438 2021 0.154986903071404 2022 -0.0251202769577503