people have lived
people can live longer
an average life is extended
human lifespan is prolonged
the proportion between of
As an illustration of this is Japan. In this country, there been noticed a significant disproportion in the population
For instance, due to a significant disproportion in the population of Japan
inclines to the seniours-friendly society
I don't get your idea here.
Apart from the pension issue
This issue is not clearly mentioned in the first body paragraph.