Taciturn

echo $((`grep 'cie' word.list | wc -l` + `grep '[^c]ei' word.list | wc -l`)) / `grep -E '(ie)|(ei)' word.list | wc -l`

3493 / 18751

Hardly an exception to a rule.

Using the "YAWL" word list from http://personal.riverusers.com/~thegrendel/software.html.