Year	Number
1996	11.10608
1997	10.83339
1998	11.25663
1999	13.39514
2000	12.07815
2001	12.97855
2002	12.73495
2003	13.12472
2004	12.75294
2005	12.39852
2006	12.071
2007	11.85303
2008	11.73918
2009	12.265
2010	12.40724
2011	12.28939
2012	12.61971
2013	13.58777
2014	13.43385
2016	12.92957
2017	12.71943