The graph below show the population size of four different types of wild birds in canada between 1992 and 2006

The line graph illustrates data on the quantity of breeding pairs of 4 types of bird in Canada from 1992 to 2006. Overall, the populations of mallard and Canada goose have a tended to increase over the years, while the numbers of blue-winged teal and American black duck still remained relatively stable over given periods. […]