Year	Number
1999	11.94194
2000	13.37017
2006	17.62454
2010	15.50722
2011	15.97902
2012	15.90263
2013	14.6531
2015	12.97519
2016	16.37131
2017	13.43373
2018	16.54056
2019	15.07117