Historical clue formulations

• Intl. group formed in 1945 — 2026-05-17
• Country band, for short? — 2022-07-06
• Secretariat's org. — 2015-05-24
• Human Development Report publisher, in brief — 2013-08-24
• N.Y.C. landmark — 2011-09-11
• One of its official languages is Eng. — 2011-04-08
• Org. headquartered on N.Y.C.'s First Avenue — 2010-03-24
• N.Y.C. country club? — 2008-07-23
• Country club? — 2005-07-15
• Kofi Annan's bailiwick — 2004-05-28
• It originally included 51 states — 2001-08-17