Historical clue formulations

• "Beats me!" — 2026-09-07
• [Shrug] — 2025-04-29
• "I haven't the foggiest" — 2023-09-27
• "Haven't the foggiest!" … or, when the first two letters are put at the end, an essential part of seven answers in this puzzle — 2023-08-31
• "Beats me" — 2022-04-26
• "Beats me!" — 2021-04-30
• "I haven't the foggiest!" — 2018-05-19