Year	Number
1971	64.89023
1972	66.0043
1985	64.19181
1986	70.64574
1989	68.37361
1990	67.18043
1991	65.81015
1992	62.30879
1994	60.91016
1995	62.05484
1996	62.95828
1997	67.07802
1998	67.5661
1999	67.88426
2000	68.62067
2001	71.22252
2002	67.9511
2003	72.11578
2004	68.7188
2005	63.15438
2006	62.72308
2007	60.37925
2008	62.40153
2009	61.01961
2010	62.20393
2011	62.59056
2012	61.26763
2013	62.42763
2014	56.16602
2015	55.54179
2016	56.88788