Year	Number
2002	18.42509
2003	16.50349
2004	15.83098
2005	15.1617
2007	17.12162
2008	15.58283
2009	15.48291
2010	15.00049
2011	14.79031
2012	14.68737
2013	15.73995
2014	15.35495
2015	15.14833
2016	15.55688
2017	15.69344