NEW YORK. New York City is lagging well behind the rest of the nation in returning its census forms. As of yesterday, only 48 percent of city households had sent back their questionnaires compared to a 62 percent return rate nationwide. Mayor Michael Bloomberg urged residents to get their forms in before the April 15 deadline, explaining the consequences: for each person not counted in the census, the city loses $3,000 in federal aid a year for needed services.