Year	Number
1960	1.6107520438712255
1961	1.4296963978184107
1962	1.4625692473745358
1963	1.6573248565159817
1964	3.0758811225887275
1965	3.573254384651735
1966	2.644063983024813
1967	3.7501784999286003
1968	6.260382681032113
1969	3.286107831562377
1970	3.129101063376766
1971	2.095186762884101
1972	2.3530292653896554
1973	2.7403512869575586
1974	2.9051228884497102
1975	2.323007424838827
1976	2.2365654949590428
1977	0.9192798839693387
1978	1.0899356454683595
1979	3.592359693122876
1980	4.562912973949774
1981	3.664594044162404
1982	8.920311336339319
1983	6.989322247472659
1984	12.60784329349905
1985	14.337536335200413
1986	6.394232498417222
1987	13.831365577243869
1988	9.48145853107425
1989	13.348087167515665