proportion of population aged 65 and over in Japan Sweden and USA

The line graph compares the percentage of elderly people in usa, sweden, japan over a course of 100 years, starting from 1940, including predictions through 2040.
Overall, it is evident that the proportion of people aged 65 or over all experienced an increase in three countries over the period shown, with the most dramatic rise taken place in japan's figures.
In 1940, usa had the largest proportion of old people at around 9%, which was followed by sweden and japan approximately 6 % and 5% respectively. over the next 60 years, while sweden and usa has witnessed a steady rise in figures to roughly 15%,the proportion of people older than 65 in japan fluctuated slightly, with figures return to its starting figure in 1940.
Despite remaining at a relatively low number, japan is predicted to have nearly 27% of its population is elderly people in 2040, with an exponential growth of five times in the last 40 years. The proportion of population aged 65 or over in usa and sweden, with the former expected to increase more slowly than the latter, reaching a high of 23% and 25% in turn in 2040. usa's percentage of old people is the least among the three countries despite having the highest start at 9%.