Year	Number
1999	16.47991
2000	16.40669
2001	16.94009
2002	17.86431
2003	17.33935
2004	15.70491
2005	16.42819
2006	16.45897
2007	16.54423
2008	16.5503
2009	17.21514
2010	17.10019
2011	15.43893