Year	Number
1996	22.8723411560059
1998	17.5531921386719
2000	24.8677253723145
2002	21.6931209564209
2003	19.0954780578613
2004	19.9029121398926
2005	19.4174766540527
2006	17.8743953704834
2007	18.3574886322021
2008	17.3076915740967
2009	19.9052124023438
2010	14.2180099487305
2011	17.0616111755371
2012	19.4312801361084
2013	18.0094795227051
2014	18.5714282989502
2015	19.0476188659668
2016	17.1428565979004
2017	25.7142848968506
2018	23.5849056243896
2019	22.6415100097656
2020	18.3962268829346
2021	17.9245281219482
2022	17.9245281219482