of events and economic collapse, the agreement between West Germany and Turkey ended in 1973 but few workers returned because there were few good jobs in Turkey. Half of the Turkish guest workers returned home, others brought in their wives and family members and settled in ethnic enclaves. In 1981 legal restrictions on the relocation of families to West Germany came into effect. In 2013 it was revealed that ex-chancellor Helmut Kohl had plans to halve the Turkish population of Germany in the 1980s. Several SPD politicians, such as former chancellor Helmut Schmidt and his chief of staff Hans-Jürgen Wischnewski, as well as Hesse Minister-President Holger Börner were also in favor of restricting migration of Turks. By 2010 there were about 4 million people of Turkish descent in Germany. The generation born in Germany attended German schools, but some had a poor command of either German or Turkish, and thus had either low-skilled jobs or were unemployed. Most are Muslims and are presently reluctant to become German citizens. Germany used the principle in its nationality or citizenship law, which determined the right to citizenship based on a person's German ancestry, and not by place of birth. Accordingly, children born in Germany of a guest worker were not automatically entitled to citizenship, but were granted the ('right to reside') and might choose to apply for German citizenship later in their lives, which was granted to persons who had lived in Germany for at least 15 years and fulfilled a number of other preconditions (they must work for their living, they should not have a criminal record, and other preconditions). Today, children of foreigners born on German soil are granted German citizenship automatically if the parent has been in Germany for at least eight years as a legal immigrant. As a rule those children may also have the citizenship of the parents' home country. Those between 18 and 23 years of age must choose to keep either German citizenship or their ancestral citizenship. The governments of the German States have begun campaigns to persuade immigrants to acquire German citizenship. Those who hold German citizenship have a number of advantages. For example, only those holding German citizenship may vote in certain elections. Also, some jobs may only be performed by German citizens. As a rule these are jobs which require a deep identification with the government. Only those holding German citizenship are allowed