The USGS reported a current total reserve base of copper in potentially recoverable ores of 1.6 billion tonnes as of 2005, of which 950 million tonnes were considered economically recoverable.[28] A 2013 global assessment identified "455 known deposits (with well-defined identified resources) that contain about 1.8 billion metric tons of copper", and predicted "a mean of 812 undiscovered deposits within the uppermost kilometer of the earth's surface" containing another 3.1 billion metric tons of copper "which represents about 180 times 2012 global copper production from all types of copper deposits."[29]