(Posted from an old draft, info may be out of date)
Idle hands do the devils work (which in this case seems to be bad statistics)
A graph gleaned from a query of Scenarios by System from the irishgaming.com scenario bank.
I don’t think its representative, the scenario bank is far from complete (through no fault of its maintainers I might add), but its probably the best reference barring trawling through convention rpgs on irishgamingwiki.com.
(The other category is made up of all the systems that have only one game logged against them)