Year	Number
1996	19.5
1998	21.3930339813232
2000	6.96517419815063
2002	10.4477615356445
2003	9.95024871826172
2004	8.17307662963867
2005	12.9807691574097
2006	18.269229888916
2007	15.384614944458
2008	18.269229888916
2009	16.5876770019531
2010	19.4312801361084
2011	19.2488269805908
2012	16.4319248199463
2013	19.2488269805908
2014	21.674877166748
2015	22.660099029541
2016	22.660099029541
2017	23.1527099609375
2018	19.4174766540527
2019	18.8405799865723
2020	19.3236713409424
2021	20.2898559570313
2022	19.3236713409424