Year Number 1996 -0.308690518140793 1998 -0.312703251838684 2000 -0.319230049848557 2002 -0.666176438331604 2003 -1.00267052650452 2004 -1.06540596485138 2005 -1.09960174560547 2006 -1.20800864696503 2007 -1.44393813610077 2008 -1.37214863300323 2009 -1.55987942218781 2010 -1.56311976909637 2011 -1.40288519859314 2012 -1.4448344707489 2013 -1.52926170825958 2014 -1.74004256725311 2015 -1.87266981601715 2016 -1.99904632568359 2017 -1.98403537273407 2018 -2.38673639297485 2019 -2.38258337974548 2020 -2.26745915412903 2021 -2.21518588066101 2022 -2.04584336280823