Overall, there was a steady increase in the proportion of elderly citizens in all three countries over the given period. In 1940, the United States had the lowest percentage of individuals aged 65 and over, at approximately 9%. However, by 2040, this figure is projected to rise to around 22%. Japan began with a slightly higher percentage of about 5% in 1940 and is expected to have the highest proportion by 2040, reaching approximately 36%. Sweden started with a higher proportion in 1940, at roughly 12%, and is anticipated to reach about 30% by 2040.