Year	Number
1997	11.19236
1998	12.35782
1999	12.12961
2000	11.30199
2001	11.37359
2002	11.7508
2003	12.43452
2004	12.61631
2005	12.79264
2006	12.61697
2007	12.52776
2008	12.45338
2009	12.50113
2010	12.1548
2011	11.86497
2012	11.53883
2013	11.5124
2014	11.3341
2015	11.37962
2016	11.35457
2017	11.32371