debtcollector is right - if anything, he's understating the situation.
Your figures are either wrong per se or wrong because they're not in context.
If judgment creditors don't collect, the reasons in the vast majority of instances are (1) ignorance, (2) laziness, (3) bankruptcy. And bankruptcy is waaaay down the totem pole.
If I take a judgment today and simply decide to do nothing but lien all of your real property for 10 years, is the judgment uncollected? If I accepted YOUR payment plan and took installments for 5 years, the judgment is uncollected now, but is it uncollected per se?. Does your 80% take into consideration events 5-10 years into the future?
Sorry, DC is correct, and I speak for post-judgment - the part he's not addressing.