Year	Number
1961	17.53310118637891
1962	18.828050536391473
1963	19.978768148178105
1964	21.382707114568884
1965	22.56756217316674
1966	24.433134292469845
1967	27.627571893272666
1968	28.971730599823818
1969	30.701950528060053
1970	31.987117040100202
1971	32.25203502951275
1972	34.25209858045679
1973	37.22894991187674
1974	40.62325369219365
1975	44.23046627346257
1976	47.387312829593135
1977	50.499396675878714
1978	55.859971655775134
1979	60.047593251818604
1980	66.84714989158849
1981	70.8399580797998
1982	74.52634325715815
1983	80.61490177342569
1984	86.46229809753359
1985	94.62326964526527
1986	101.01041040431636
1987	104.98215560314061
1988	108.05262567324955
1989	109.17779842220008
1990	114.64483154271409
1991	113.93291710993384
1992	113.66751517524966
1993	116.46443620855968
1994	118.54284251555497
1995	124.56616696369291
1996	124.93246140614212
1997	138.43370471135225
1998	128.16207503875398
1999	138.14961685823755
2000	163.61709910261413
2001	173.49037866448458
2002	178.14855088222927