Historical clue formulations

• Couple of high points? — 2019-06-23
• German mark — 2019-01-29
• High points? — 2018-04-13
• Mark in the intersection of 17-Across and 1-Down — 2016-06-01
• One of two used facetiously in Mötley Crüe — 2013-09-17
• One seen in Häagen-Dazs — 2005-08-19