Government statistics show 21,500 homicides in the first half of this year, compared with about 25,000 for the entire year of 2007, Calderon???s first full year in office.Calderon praised the transformation of the federal police, which he said has grown from 6,500 officers to 37,000 during his term, including 8,600 college graduates ??? a reform forced by the repeated failure of similar overhauls