Square, Enix, and Square Enix: Sales, Titles, and Average per system.
Source = Famitsu, per Garaph

Raw Data (per title) HERE.

Significant point, JJ. On top of that, I would caution our readers from reading too heavily into the "avg per title" chart simply because it rewards the system with the fewest games.

It would be interesting to see what the averages would look like if the budget releases were combined into one record.

I'm counting 15 budget and international releases in the PS2 list. Is that what you're getting?

That would change the avg from 334,153 to 416,321, ranking it above everything above the DS (without checking for similar releases on other systems).