Nicko, what I think you'll find is a "viscious circle":
There is no real "average" wage for cooks because there is no benchmark or standard that represents what a Cook should know or be capable of. This is the center of the circle.
Round and round we go, because since there is no benchmark, there is no pay scale to hang on to the job.
Round and round we go, because although we do have Unions, they have no interest in setting forth a benchmark.
Round and round we go, because since we have no benchmark, the Culinary schools can teach any curriculum they want to, with courses as long or as short as they deem neccesary, with whatever content they deem neccesary.
Now, compare this whole mess with other trades like plumbers/ gasfitters or electricians. There you will find benchmarks that are built into teaching curriculum, built into building codes, and a rising salary scale based on the various benchmarks to be achieved. The respective Unions work closely with the teaching facilities, developing curriculum, and with the various municipalities, enforcing codes that are part of the curiculum.
A cook out of a 1 yr culinary school with no previous working experience can earn anywhere from buck minimum to maximum $20.00/hr. A plumber in his first year will earn that without even asking, as there are payscales based on 1st year benchmarks.
No one is interested in setting benchmarks for the cook. True, there are benchmarks set forth by the AFC, but these are for Chefs, not cooks, In many parts of Europe the emphasis is on developing the cook, NOT the Chef, as it is impossible to have a good Chef that is not a competant cook. You can look at it as, "Take care of the pennies and the dollars will take care of themselves", or you can look at it that every professional sports team has a Coach that was once first a competant professional player.
It's a nasty little circle......................