Hi,
1. そして、その程度は国民の総医療費を国民全体で負担することによって成り立っている。
I would guess this ought to mean "This system was established so that the nation's medical bill would be borne by the country as a whole."
However, I do not really understand によって成り立っている. The definitions that I find in the dictionary for によって and 成り立つ do not seem to work.
2. 世界一の長寿国になったといっても、実は喜んでばかりもいられない。
I'm guessing this roughly means "Although (Japan) became the country with the world's highest life expectancy, it is in fact not all good news."
Is いられない the negative potential form of いる (居る)? In what sense is this used? Is it esentially 喜んでいられない with ばかりも inserted?
3. そんなことは前から分かっていたことではないかと思うかもしれないが、実は寿命が伸びるスピードが予想以上に速かったのである。
I believe the second part of this means "in fact, the increase in life expectancy was faster than expected"
The first part looks to me like "Maybe I wonder whether you/someone didn't know that before, but...", but this doesn't sound correct in English. I don't think I properly understand it.
2078. NAJPAC 118.C
それに対して、日本はなんと24年しかかからなかったのである。
I believe this means "In contrast, Japan took only 24 years [to achieve a particular longevity statistic]", but what is the purpose of なんと?