Year	Number
1996	0.373912304639816
1998	0.345668405294418
2000	0.342506408691406
2002	0.316015273332596
2003	0.301584661006927
2004	0.293032377958298
2005	0.286872625350952
2006	0.257249593734741
2007	0.244294539093971
2008	0.246047765016556
2009	0.246055126190186
2010	0.243547096848488
2011	0.244249582290649
2012	0.233037114143372
2013	0.238264307379723
2014	0.205589711666107
2015	0.208575189113617
2016	0.21855928003788
2017	0.227142184972763
2018	0.225699260830879
2019	0.240575924515724
2020	0.237614139914513
2021	0.239949867129326
2022	0.239937707781792