Historical clue formulations

• Every now and then — 2026-04-24
• Occasionally — 2017-10-01
• Occasionally — 2014-08-30
• Occasionally — 2013-01-14
• Occasionally — 2011-09-29
• Intermittently — 2011-02-26
• Now and again — 2009-02-10
• Now and then — 2007-07-08
• Occasionally — 2006-05-31
• Now and then — 2003-06-11
• Periodically — 2001-04-28
• Periodically — 2000-12-16
• Now and then — 2000-12-04
• Once in a while — 2000-08-12
• Now and again — 1998-10-10
• Not always — 1998-05-19
• Now and then — 1997-01-15
• Now and then — 1996-07-05
• Occasionally — 1994-07-09