Year	Number
1996	0.373912304639816
1998	0.345668405294418
2000	0.342506408691406
2002	0.316015273332596
2003	0.301584661006927
2004	0.293032377958298
2005	0.286872625350952
2006	0.27938786149025
2007	0.267617672681808
2008	0.271060198545456
2009	0.272184789180756
2010	0.267576217651367
2011	0.260717630386353
2012	0.242201656103134
2013	0.247866421937943
2014	0.210570260882378
2015	0.213650554418564
2016	0.21855928003788
2017	0.227142184972763
2018	0.218196511268616
2019	0.222056418657303
2020	0.217306077480316
2021	0.220321893692017
2022	0.228340446949005