The important point, however, is say it is early in the game and you are at 50 AIP (so Mark I enemy ships). The first CPA is announced for 200 ships. But you've killed all the Mark I ships in the galaxy. The CPA will contain 200 Mark IIs. But what if somehow you've killed all the Mark IIs? It'll contain 200 Mark IIIs. What if you've killed all the Mark IIIs and IVs too! That's right, 200 Mark Vs.
So the moral is, be careful about clearing out low mark ships unless you don't mind CPAs pulling higher Marks.