Here are some numbers I dug up a few years ago for percent fat content by species. Of course these can vary a lot by run location and individual fish.

Spring Chinook - 22%
Fall Chinook - 11.4%
Sockeye - 7.6%
Pink - 6.7%
Farmed Atlantic - 6.3%
Coho - 4.6%
Chum - 3.8%
Halibut - <1%