Year	Number
1997	14.00258
1998	15.60097
1999	12.49291
2001	10.29705
2002	10.93296
2003	9.47933
2004	10.93515
2005	8.61468
2006	20.21437
2010	17.77662
2011	23.86224
2013	14.91685
2014	20.6143
2015	16.55996
2016	17.53851
2017	18.10378