"Year","After 10 years","After 15 years","After 20 years"
1942,,6.309264,6.61294
1943,,4.041476,4.411467
1944,,2.746634,3.419528
1945,,4.279295,5.558078
1946,4.668821,6.451905,8.346303
1947,4.870843,7.227245,9.333956
1948,5.093701,7.227889,9.377592
1949,4.905854,7.075297,9.226507
1950,4.03402,6.260974,8.197903
1951,2.987116,5.104269,6.845435
1952,2.504120,4.584051,6.315487
1953,2.556854,4.817707,6.696053
1954,2.714667,5.104619,7.249212
1955,2.742421,5.176023,7.610786
1956,2.576837,5.180637,7.82137
1957,2.365070,5.324197,8.120254
1958,2.964839,5.642211,8.597674
1959,3.070742,5.764126,8.735855
1960,2.860896,5.456679,8.724639
1961,3.093406,6.262308,8.848
1962,2.716079,5.613987,8.433271
1963,2.834322,5.810398,8.57527
1964,3.010711,6.02534,8.861591
1965,2.862393,6.098711,9.054481
1966,2.570812,5.733962,8.674953
1967,2.497295,5.520923,8.375789
1968,2.460056,5.472346,8.547339
1969,2.792871,6.090713,8.909953
1970,3.034137,6.633114,9.558915
1971,3.422615,7.251397,10.02723
1972,3.481323,7.443986,10.24995
1973,3.468598,7.453529,10.35903
1974,3.677142,7.551743,10.48666
1975,3.824124,7.702013,10.68338
1976,3.839023,7.612544,10.54147
1977,3.749087,7.544743,10.19038
1978,3.536695,7.41009,9.887846
1979,3.502420,7.349198,9.57558
1980,3.68138,7.320699,
1981,3.728445,7.262035,
1982,3.783736,7.277773,
1983,3.7492,7.200639,
1984,3.461972,6.730623,
1985,3.211835,,
1986,2.994109,,
1987,2.98295,,
1988,2.854442,,
1989,2.934981,,