The fact that they do not keep such a record is conspicuous by its absence because if they did we could work out exactly how many there have been since the founding of the WBT$. Hypothetically, that number, coupled with the number of Christians from the first century until Russel would, without doubt, exeed 144,000 and would expose the doctrine for the lie that it is.
The thread that deals with this crucial topic is fascinating and worthy of more research.
Obviously our research has limitations but I always struggled to believe that the number of 144,000 had not been exeeded. I'm certain that they knew this and the 'Great Crowd' teaching was a direct response to this which would, of course, create somewhere for the surplus to go.
Sorry to repeat myself, but this always nagged at me in the back of my mind like an alarm and I don't think I ever really bought in to it.