The figure shown is a graph published by Statistics Sweden. It compares Swedish society in 1750 and in 2010 on the numbers of men and women of various ages, using age pyramids. Explain how this indicates that
a. In 1750, few Swedish people were old.
b. In 2010, Sweden had many more people than in 1750.
c. In 2010, of those who were very old, more were female than male.
d. In 2010, the largest five-year group included people born during the era of first manned space flight.