Ray,
Commercial artilleries are not common.
In the earlier part of the century .30 was very popular and plentiful. The early Luger models were chambered for it--it was an "in-house" round--and these were the very prevalent "big gun" auto-loaders of the era. In the years between the two World Wars German arms manufacturers were prohibited from manufacturing handguns in "military" calibers (i.e. 9mm), so almost all of the Lugers of those years were made in cal. .30 Luger. Many of the commercial artillery and long-barrel Lugers proudced for export in the '20s are found in .30.
I don't know the proportions, but I'd field a WAG that your 9mm gun is probably less common.
--Dwight
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