Year	Number
1996	-0.546156048774719
1998	-0.537084102630615
2000	-0.506055653095245
2002	-0.560230851173401
2003	-0.483061969280243
2004	-0.476456582546234
2005	-0.594401121139526
2006	-0.930595397949219
2007	-0.834666192531586
2008	-0.721992611885071
2009	-0.579241037368774
2010	-0.593127608299255
2011	-0.778770327568054
2012	-1.1284441947937
2013	-1.40619838237762
2014	-1.35771584510803
2015	-1.43519008159637
2016	-1.99247241020203
2017	-2.09612011909485
2018	-2.05405068397522
2019	-2.08743524551392
2020	-2.08732032775879
2021	-2.08200311660767
2022	-2.06944227218628