Year	Number
1971	21.38035
1973	20.35294
1974	21.00253
1975	21.00373
1995	10.99441
1996	12.15728
1997	11.69532
1998	11.5149
1999	11.94556
2000	11.96316
2001	12.70697
2002	12.46537
2003	12.20221
2004	12.2579
2005	11.96926
2007	11.42551
2008	11.42579
2009	11.24436
2010	11.03099
2011	10.76512
2012	10.61937
2013	11.85033
2014	11.52599
2016	11.53925
2017	11.14189