Year	Number
1996	-2.50936651229858
1998	-2.14295434951782
2000	-1.94878721237183
2002	-2.36895203590393
2003	-2.57482099533081
2004	-2.87853956222534
2005	-2.70559000968933
2006	-2.74635028839111
2007	-3.22849702835083
2008	-3.28051733970642
2009	-3.31295108795166
2010	-3.13097143173218
2011	-3.08384656906128
2012	-2.860755443573
2013	-2.75868654251099
2014	-2.51582813262939
2015	-2.37008881568909
2016	-2.34715795516968
2017	-2.2499098777771
2018	-2.24898767471313
2019	-2.38628840446472
2020	-2.58138513565063
2021	-2.72717571258545
2022	-2.48343443870544