I help out with a national dog rescue group here in Australia...which is a large island continent. The group keeps contact with all the breed rescue group & all the animal refuges & pounds.
It's really clear that different types of dogs are more popular in different parts of the country. This seems to be partly due to the different lifestyles people live. For example, refuges in the big cities & in areas where there are many retired people, find that people want the smaller to middle-sized breeds. But the working-dog breeds are not so popular in these areas. They tend to be kept by people living on the fringes of the cities or in the rural areas.