Year	Number
1996	13.5
1998	14.9253730773926
2000	14.9253730773926
2002	12.4378108978271
2003	12.93532371521
2004	12.5
2005	13.942307472229
2006	12.9807691574097
2007	9.61538505554199
2008	9.13461494445801
2009	10.9004735946655
2010	22.274881362915
2011	23.9436626434326
2012	17.8403759002686
2013	18.3098583221436
2014	24.1379318237305
2015	24.1379318237305
2016	25.1231517791748
2017	25.6157627105713
2018	25.7281551361084
2019	25.6038646697998
2020	23.1884059906006
2021	21.2560386657715
2022	19.3236713409424