Notes on a bunch of things relating to population

     Fertility and mortality rates vary not only spatially,but also temporally within a country. A dependency ratio is the number of people who are too young to work or too old to work, compared to the number of people in their productive years. People from the ages of zero to fourteen and sixty-five and older are considered to be dependents. Larger dependency ratios mean that there is a higher financial burden on the working class. Sex ratio is the number of males per 100 females in the population. Developed countries have more females than males since females tend to outlive men by about seven years.