Here are the rain stats for Seattle since 1948. While 2016 had a bit more rain than usual, it was by no means an outlier in any sense of the word.

http://www.seattleweatherblog.com/rain-stats/

If we take a look at an entire different arbitrary set of stats, Oct 20, 2003 had the highest amount of rain in a single day period at 5 inches. That was memorable.