Year	Number
1970	9.75032
1972	10.09979
1973	9.08782
1974	11.15682
1979	15.86602
1982	11.39907
1987	12.34767
1990	18.13189
2003	15.52784
2004	15.52386
2009	28.48145
2011	31.89532
2014	23.89329
2018	21.52832