Year	Number
2004	17.9104480743408
2005	18.6274509429932
2006	14.2156858444214
2007	12.1359224319458
2008	10.6796112060547
2009	9.09090900421143
2010	9.56937789916992
2011	14.2180099487305
2012	15.6398105621338
2013	14.2180099487305
2014	12.0192308425903
2015	15.7142858505249
2016	14.7619047164917
2017	20.9523811340332
2018	18.0952377319336
2019	17.619047164917
2020	20
2021	20
2022	21.698112487793