Year	Number
1996	-1.42351043224335
1998	-1.62168252468109
2000	-1.63589775562286
2002	-1.31669890880585
2003	-1.22716307640076
2004	-1.27209603786469
2005	-1.17462551593781
2006	-1.41659390926361
2007	-1.59721124172211
2008	-1.60734331607819
2009	-1.70581245422363
2010	-1.70923280715942
2011	-1.52120280265808
2012	-1.4260185956955
2013	-1.49050867557526
2014	-1.45748889446259
2015	-1.33899629116058
2016	-1.24572420120239
2017	-1.22047603130341
2018	-1.39584970474243
2019	-1.44250011444092
2020	-1.48580825328827
2021	-1.63386595249176
2022	-1.59271132946014