Year	Number
1961	0.9966777408637874
1962	1.052048726467331
1963	1.1013215859030838
1964	1.1904761904761905
1965	1.2458471760797343
1966	1.7718715393133997
1967	2.308960967564596
1968	2.803738317757009
1969	3.3534909290819135
1970	4.065540194572453
1971	4.09626216077829
1972	4.37956204379562
1973	4.9422632794457275
1974	5.688073394495413
1975	8.769931662870158
1976	7.149321266968325
1977	7.820224719101124
1978	8.526785714285715
1979	9.223946784922395
1980	11.07488986784141
1981	10.576923076923077
1982	11.306510734857742
1983	11.720111537120948
1984	12.049765094832086
1985	12.087387074357192
1986	13.876843018213355
1987	15.587114651887774
1988	17.369877226353104
1989	19.423342541436465
1990	21.54800896397173
1991	23.846815834767643
1992	33.515232243372154
1993	43.33647987642667
1994	53.12995415399118
1995	62.895772719493415
1996	72.63405255287331
1997	82.55823875757318
1998	92.45451834178347
1999	102.11027910142954
2000	111.72472387425658
2001	123.01910828025477
2002	124.0728051391863
2003	125.14470842332612
2004	125.9608695652174
2005	127.0657894736842
2006	128.19026548672568
2007	129.33482142857142
2008	130.5