Year Number 1996 0.273877173662186 1998 0.412275731563568 2000 0.153456091880798 2002 -0.0942921563982964 2003 -0.250032126903534 2004 -0.0683272704482079 2005 -0.121956370770931 2006 -0.237762182950974 2007 -0.188574343919754 2008 -0.117300540208817 2009 -0.14176744222641 2010 -0.0508231818675995 2011 0.141080409288406 2012 0.104277603328228 2013 0.0936860963702202 2014 0.247864335775375 2015 0.279361039400101 2016 0.277257770299912 2017 0.269298404455185 2018 0.230616614222527 2019 0.081537127494812 2020 0.110377036035061 2021 0.239029332995415 2022 0.357974648475647