Year	Number
1961	115.96291012838802
1962	118.91737891737891
1963	123.97727272727273
1964	142.5070821529745
1965	160.3617945007236
1966	176.33093525179856
1967	129.19770773638967
1968	133.43151862464182
1969	142.6356005788712
1970	146.35160349854226
1971	152.79853747714807
1972	158.61771217712177
1973	159.83567567567567
1974	159.77062735933848
1975	166.36245487364621
1976	166.2490566037736
1977	161.92013093289688
1978	351.43617021276594
1979	355.8028616852146
1980	313.58090185676394
1981	374.1182854042322
1982	391.8435754189944
1983	408.2901554404145
1984	409.9145299145299
1985	424.60824143934997
1986	488.7281035795887
1987	486.44362208292426
1988	486.946736684171
1989	491.92882348524665