They are related. When you have a mixed economy lowlifes are attracted to moving there. They didn't import them the people moved themselves. They may have allowed them to move there which was a mistake, but even if you don't allow them they come illegally (see America). How much welfare your economy has is much more related to the number of untermench your nation attracts than any immigration policy. Welfare breeds untermench and untermench go where they can be bread.