Year	Number
1960	3.7112551413570545
1961	3.5997798697440064
1962	4.497773422551808
1963	4.678307876479333
1964	6.854731831861402
1965	5.989084952141186
1966	6.411528087138446
1967	6.319977059644765
1968	7.367065152273953
1969	8.987347232453082
1970	15.198117718842338
1971	6.36093527156657
1972	5.209592429541687
1973	5.285546302899981
1974	1.291593814827213
1975	1.6618501747487346
1976	2.331903517311565
1977	2.120262842761406
1978	2.5977615456063488
1979	2.6274989456742004
1980	4.398931542254444
1981	17.56470591894805
1982	9.065373049585297