Year	Number
2000	18.56665
2001	18.36946
2002	18.16583
2003	18.55978
2004	18.28019
2005	18.3965
2006	18.85524
2007	18.77087
2008	18.15276
2009	18.48588
2010	18.89904
2011	19.73245
2012	19.71396
2013	20.10427