Name all U.S. Ambassadors to United Nations

The Ambassador to U.N. is the leader of the U.S. mission to the united Nations. They represent the U.S. on the U.N.Security Council and during all meetings of the General Assembly unless if there is a more senior U.S. officer present like the Secretary of State or the President. The Ambassador has gone between being a cabinet level position to not being one throughout several administrations.