 Complete the following phrase:  Duisburg celebrated its 1100th anniversary in 1983. The citys population recovered a little in the following years, up to 537,000 in 1992. It declined to 488,000 in 2011. On 19 July 2004, it was hit by a tornado. The municipal theater and parts of the city center were damaged. The city hosted the 7th World Games in 2005. In 2010, 21 people died because of a mass panic at the 