Year	Number
1996	10.25311
1997	11.06716
1999	12.34155
2000	12.80956
2001	11.56422
2002	12.00039
2003	13.14088
2004	11.70098
2005	10.56873
2006	9.89097
2007	9.52812
2008	9.44032
2009	9.49201
2010	10.17207
2011	10.35661
2012	9.40386
2013	9.05182
2014	8.88597
2015	9.43335
2016	9.74432
2017	9.73065
2018	9.71138