Yes, if you start from a base of 25 years (which is the extreme low end of the range from your source), then we have 30 years of increase from reduced infant/ch

Yes, if you start from a base of 25 years (which is the extreme low end of the range from your source), then we have 30 years of increase from reduced infant/child mortality and 25 years of increase from reduced adult mortality. Can you really look those numbers and say that one of them is highly significant while the other "has not changed much"? Translating this into percentages or "fold" increases is misleading because you are using a different denominator for the two increases. E.g. you are claiming that reduced infant mortality is a 2.2-fold increase (55/25) while reduced adult mortality is "only" a 1.45-fold increase (80/55), even though the number of years gained is almost the same. And if you use the other end of the 25–40 year range, then reduced infant mortality is "only" a 1.38-fold increase (55/40).