Observed (1851 to 2011) and projected (2011 to 2061) annual average growth rate, natural increase and migratory increase in Canada per intercensal period Two factors are behind population growth: natural increase and migratory increase. 1  Natural increase is the difference between the number of births and deaths during a given period. 2  Migratory increase is the difference between the number of immigrants entering the country and the number of emigrants leaving the country.
Why do we have wisdom teeth? Adults can have up to 32 teeth. The wisdom teeth are the last to appear, right at the back of the mouth. They usually appear when you are between 17 and 25, although sometimes they appear many years later. People often have jaws that are too small for all 32 teeth to fit - 28 is often the most we have room for.
Also called third molars, wisdom teeth are the third and last set of teeth to appear in a person's mouth, usually between ages 17 and 25. There are typically four wisdom teeth, two on top and two on the bottom.