How many apostates are becoming witlesses? Only those who they successfully recapture (and there is a sky high cost of doing that, so they generally only do that in cases where they feel there is exceptionally high value in doing so), those with family ties and wishing to see their families again, and those who find themselves unable to do their own thinking (or are too lazy). Most apostates would just as soon stay that way--those returning for family are actually wanting to get their families out of the cancer (this is probably why the Filthful and Disgraceful Slavebugger pushes so hard to get the whole family in--so they will have a miserable time if they ever leave themselves).
In the world, relatively few people are coming in. Up to about 1993, the witlesses could come to the door and give people their only exposure to the Bible, and they would have few resources to verify it. From that point on, anyone could research with a mouse click (and that is getting worse by the year). Most of the people coming in these days are either very poor, have a mental issue, under severe duress of whatever kind, or are drunk or stoned when they accept the study. These are the ones that are easily defrauded into joining (promise of the opposite sex, a better job, freedom from illness, or being able to have material things). Some will fall for that scam.
Basically, all that's left is family that is born in. They are going to push bringing in men from outside, but I predict that there will be more false hope, bumbling (continuing to study without making progress), and failures to generate interest than anything. One could regular pio-sneer for 4 years (and be sincere, doing everything so as to succeed, and not dogging it), just look for men, and be lucky to get even one--while spending almost 3500 hours working around and on men, kissing men's butts in an attempt to get them to progress, and finding close to 100 of them (or more) just to have a 30% chance of getting one of them to join.