U.S. firms lead EU lobbying league

* U.S. companies dominate top spending rankings * Tech rivals Microsoft, Google among big lobbiers * Oil giants maintain high spending, Deutsche Bank grows * Data deadline was first since registration mandatory By Alastair Macdonald BRUSSELS, April 30 (Reuters) - U.S. companies, including tech rivals Microsoft and Google, were among leading spenders on corporate lobbying in Brussels last year, a Reuters review of new data showed (table below). Companies had until Thursda