Year	Number
1996	-1.85870087146759
1998	-1.81138920783997
2000	-1.75222194194794
2002	-1.54347372055054
2003	-1.65719187259674
2004	-1.66658997535706
2005	-1.71884191036224
2006	-1.7393399477005
2007	-1.64922380447388
2008	-1.64158809185028
2009	-1.68687272071838
2010	-1.72558903694153
2011	-1.77131509780884
2012	-1.77434039115906
2013	-1.77589881420135
2014	-1.73637986183167
2015	-1.78320395946503
2016	-1.83413589000702
2017	-1.83911836147308
2018	-1.84886014461517
2019	-1.65239012241364
2020	-1.42925202846527
2021	-1.4574955701828
2022	-1.50051319599152