mar2603,
CO also thinks so.
He has repeatedly asked USCIS for this information, but USCIS have said it is not available.
USCIS are either lying, too lazy, want to score a political point, or USCIS systems are so antiquated that they lack the ability to generate the report. Take your pick.
For cases that DOS process through CP, USCIS has to send them the approved I-140 and DOS do compile those figures (including dependents if mentioned on the I-140).
DOS publish a
Summary document (not broken down by PD year unfortunately) annually.