Every two years the FCC is required to report to the Congress on how the DNC registry is doing.
It's doing great, over 222 million numbers registered. Since registrations no longer expire, they've done a fair amount to remove numbers when they go out of service, with a digression about how you tell a number that's been disconnected from one that's been ported.
They are painfully aware of how many crooks ignore the DNC rules and how hard it's become to enforce with cheap global VoIP and the ability for any random virtual PBX to inject call data that used to need a CO switch and SS#7.
Find all about their "Zapping Rachel" contest, too.