Year	Number
1961	9.137829912023461
1962	9.178885630498533
1963	9.473684210526317
1964	9.941520467836257
1965	11.661807580174926
1966	13.486880466472304
1967	14.244186046511627
1968	15.743440233236154
1969	16.86046511627907
1970	17.971014492753625
1971	19.653179190751445
1972	21.32564841498559
1973	24.137931034482758
1974	28.20878494010268
1975	29.651162790697676
1976	31
1977	32.96969696969697
1978	34.559006211180126
1979	37.21518987341772
1980	40.19455252918288
1981	42.775
1982	46.30154639175258
1983	47.43589743589743
1984	48.25396825396825
1985	49.056603773584904
1986	49.84423676012461
1987	50.742574257425744
1988	51.69230769230769
1989	54.32722678458622
1990	54.239401496259354
1991	53.52798053527981
1992	54.5009185548071
1993	56.7240280433397
1994	87.29179518815546
1995	90.21601016518424
1996	88.98568761667704
1997	90.11808576755749
1998	90.82397003745318
1999	90.6832298136646
2000	90.66831683168317