Year	Number
1971	13.1519
1972	14.52872
1973	14.00297
1974	15.90823
1975	16.26994
1979	26.89275
1981	36.19361
1986	37.69777
1992	35.66527
1993	44.81257
1994	39.28135
1995	42.81274
1998	38.30613
2001	52.59989
2007	47.58272
2011	28.38067
2012	25.2772
2018	35.52046