Year	Number
2001	10.6015
2003	13.27574
2005	12.56341
2006	12.3684
2007	12.07682
2008	12.34621
2009	12.18396
2010	11.89205
2011	9.3098
2012	9.05681
2013	9.06589
2014	8.94514
2015	8.78575
2016	8.70821
2017	8.63783