Immigration to modern Germany has generally risen and fallen with the country's economy. The economic boom of the 2010s, coupled with the elimination of working visa requirements for many EU citizens, brought a sustained inflow from elsewhere in Europe. Separate from economic trends, the country has also seen several distinct major waves of immigration. These include the resettlement of ethnic Germans from eastern Europe after World War II, the guest worker program of the 1950s–1970s, and ethnic Germans from former communist states claiming their right of return after the breakup of the Soviet Union. Germany also accepted significant numbers of refugees from the Yugoslav wars in the 1990s and the Syrian civil war.