Year	Number
1961	65.14816556914394
1962	74.02262879152623
1963	83.53310778153697
1964	93.0311004784689
1965	100.88792896568275
1966	108.16610657705232
1967	113.10178485287024
1968	122.26287915262397
1969	127.47715247715247
1970	129.44954128440367
1971	133.76089060987414
1972	140.50387596899225
1973	145.63106796116506
1974	151.2933138116154
1975	163.47990902198634
1976	166.2766497461929
1977	165.1511303022606
1978	164.07794192562403
1979	162.8047215807031
1980	161.9231774235694
1981	158.26882845188283
1982	156.06076479832373
1983	152.80954879328436
1984	148.93617021276594
1985	144.7795275590551
1986	141.86959937156323
1987	140.23529411764707
1988	139.7890625
1989	139.43087318087316
1990	135.82728215767634
1991	130.43219461697723
1992	117.15097603162836
1993	92.12650750676839
1994	94.35141214696326
1995	95.79789894947474
1996	92.43397573162027
1997	91.67054443927408
1998	113.12217194570135
1999	114.30408049189491
2000	98.43732274532047
2001	94.0351889241419
2002	95.59165424739196
2003	95.11284983448691
2004	93.45608210081497
2005	114.25149700598803
2006	131.0536398467433
2007	149.9481361426256
2008	171.9559585492228