to alleviate widespread unemployment. The biggest sectors for which migrants were recruited to Germany were mining, construction and manufacturing. Companies recruiting Italian workers were concentrated primarily in Germany's southeast, especially the industrial states of Baden-Württemberg, North Rhine-Westphalia, Bavaria and Hesse. Today, these regions are home to the country's biggest Italian-German communities. In 1973, due to that year's oil crisis and a resulting recession, Germany annulled the immigration treaties it had signed. However, by then the European Coal and Steel Community (later the European Economic Community), of which both Italy and Germany were members, had established freedom of movement for workers (beginning in 1968). As a result, Italians continued to be able to move to Germany for work with relative ease. An estimated 2 million Italians moved to Germany between 1956 and 1972 alone, especially from southern and northeastern Italy. The majority of Italians that came with this first wave of immigration were men without families; most intended to return there in the medium term, although a great many ended up settling in Germany permanently. From the early 1970s onward, many of these workers' families joined them. The total number of Italians who moved to Germany between 1955 and 2005 is estimated at 3−4 million. Initially seen as temporary "guest workers" by both Germany and Italy, almost no effort was made at first to ease the assimilation of immigrants into German society. Adults were not encouraged to learn German and schools were instructed to encourage students' ties to their parents' culture to promote their eventual return. Nonetheless, Italian immigrants gradually began to integrate. While most of the Italians among the 1955–1973 wave of immigrants were employed as laborers in the mining, construction and manufacturing sectors, they began to diversify into more skilled employment, especially in the automotive and electronics industry and mechanical engineering. A growing market for Italian cuisine among the local German population also led many to open restaurants. These trends contributed to the gradual upward mobility of Italian immigrants and their descendants. After reunification (1990–present) Socioeconomic indicators on immigrant groups in Germany are generally hard to come by, since most studies collect data only on the basis of citizenship, which excludes German citizens of Italian descent. However, a study in 2005 showed that Italian-German students remain over-represented in the lower tier of German secondary education (Hauptschulen) and underrepresented in the middle and highest tiers (Realschulen and Gymnasiums). They also