Year	Number
1996	2.10743379592896
1998	2.05728626251221
2000	2.13987302780151
2002	2.26273369789124
2003	2.1691677570343
2004	2.30114579200745
2005	2.15609812736511
2006	2.17491722106934
2007	2.23121237754822
2008	2.23161792755127
2009	2.20672035217285
2010	2.17136287689209
2011	2.10299706459045
2012	2.11570811271667
2013	2.07050251960754
2014	2.06756377220154
2015	2.05084657669067
2016	2.04159116744995
2017	2.08804154396057
2018	2.13455390930176
2019	2.12010598182678
2020	2.11831736564636
2021	2.13980793952942
2022	2.09472370147705