For each year, the age with the greatest increase in survival over the past 100 years (or since the earliest year for which data was available), that is, the peak of a graph like that from Extended Data Fig. 4, was determined. Including France (Fig. 1d), a total of 82 data sets were considered (males and females in each region); we used linear regressions of segments of the data to look for evidence of plateaus. A data set was considered to be plateauing if one of the following criteria applied: the second half of the data had a negative slope; the first half of the data had a negative slope (as an increase in the second half would likely reflect a return to some equilibrium after being negatively perturbed); the first half of the data had a slope greater than that of the second half of the data; or the final 10% of the data had a slope less than that of the preceding 40%. In 88% (72/82) of the data sets, there was evidence of a plateau.