Mayor Mike Bloomberg was on hand to help Former Mayor Ed Koch celebrate his 81st birthday last week at the Museum of the City of New York on Fifth Ave. “We had 225 commissioners, deputy commissioners and deputy mayors from my administrations,” said Koch, who was mayor from 1978-1989, of his invited guests. “They see serving in government, particularly those 12 years, as the highlight of their professional lives — and they’re right — and it was for me as well.”