Anecdotes and wishful tip inflation on disreputable and questionable websites perpetuated by servers and allies are plentiful.
Where can I find actual data such as the data provided to IRS(w/o names of course)...?
you can find actual data (at least what's reported) at your local Government Depository located in a library near you.
I've been looking around. Found various research papers here and there. I've yet to find one that shows the actual data table, but the so called norm of "15-20%" isn't far off and the spread isn't too wide with a few stiffs and outrageous tips here and there.