With Mike's corrections and cutting off the limit at pre-1996 because the structure changed, we get: Lars was Transport AD until 2011; 10 years. Aliisa was ART AD until 2017, no gap. Jari was Internet AD until 2012; one year. Russ was Security AD until 2007; no gap Brian Carpenter wasn't an AD unless it was before 1989 so at least a 15 year gap. Harald was Ops AD until 1999 so two year gap. Fred Baker wasn't an AD before 1989 so at least a six year gap. Or, 10 0 1 0 infinite 2 inifinite ? I don't see how you can make a compelling argument that AD->IETF Chair must not have a gap year.
