That what in the 70's started with the 1st Gastarbeiter was quite successful
See ... the guy who calls himself German, obviously doesn't know "his" country's history. Or the old man forgot. The first "Gastarbeiter" were Italians from 1956 onwards, after the first "Anwerbeabkommen" (or recruitment agreement) between the then Bundesrepublik Deutschland and Italy of December 20th 1955.
This one was followed by similar agreements with Spain and Greece (1960), Turkey (1962), Marocco (1963), Portugal (1964, the millionth "Gastarbeiter", Armando Rodrigues de Sá, a carpenter, came from there and was congratulated on the Cologne-Deutz railway station and was given a bunch of flowers, a diploma and a Zundapp moped), Tunisia (1965) and Yugoslavia (1968).
In 1973, after 4 million foreign workers had already settled in Germany there was actually a stop in recruitment because of the oil crisis.
Ah well ... I guess we are used to his factual inaccuracies.