Year	Number
1996	-2.08864450454712
1998	-1.91937220096588
2000	-1.9281210899353
2002	-1.96257197856903
2003	-1.74967467784882
2004	-1.61869239807129
2005	-1.63549697399139
2006	-1.73054528236389
2007	-1.56380665302277
2008	-1.2360702753067
2009	-1.18672871589661
2010	-1.1039627790451
2011	-1.07451224327087
2012	-1.05595529079437
2013	-1.04823577404022
2014	-1.05443298816681
2015	-1.20159161090851
2016	-1.22923362255096
2017	-1.2215883731842
2018	-1.26685917377472
2019	-1.31065630912781
2020	-1.30293536186218
2021	-1.31964814662933
2022	-1.30191540718079