The US Army Air Force and Royal Air Force dropped 2.7 million tons of bombs on Europe during World War II. In the United Kingdom, the German Luftwaffe dropped more than 12,000 metric tons of bombs on London alone. The British Ministry of Defence reported that 450 World War II bombs were made safe or defused since 2010 by disposal teams. Every year, an estimated 2,000 tons of World War II munitions are found in Germany, at times requiring the evacuation of tens of thousands of residents from their homes. In Berlin alone, 1.8 million pieces of ordnance have been defused since 1947. Buried bombs, as well as mortars, land mines and grenades, are often found during construction work or other excavations, or by farmers tilling the land.