Year	Number
1972	24.88539
1978	22.78664
1981	22.22315
1982	21.47724
1984	22.80341
1985	22.76058
1996	34.45882
2000	27.34762
2001	25.09268
2002	27.03645
2004	26.36707
2005	26.36735
2011	26.90024
2012	24.8448
2013	26.05916
2014	25.07389
2015	20.37208
2016	19.65404
2017	18.88356