pour me a glogg please

It doesn't quite fit the original greater-than-50% stipulation, so maybe we could devise a "recurrent letter index," which normalizes the percentage by dividing it by the square root of the total length of the word (or something like that). In which case

Chargoggagoggmanchauggauggagoggchaubunagungamaugg (Webster Lake to you)

has to be in the running for top honors (seventeen Gs out of 50 total letters) !