The 19.62% additional ITA were sent because of the number of rejection. We are assuming the same rejection percentage for this year which can or can not be true. Furthermore, here the profiles getting PNP are missed. Those folks will have CRS of 1000 or more and will be part of the same pool count. I think draw size of 4000 seems like more realistic figure here.
19.62% is an assumption for sure, the best we can do is predict! I don't see how the PNP numbers affect this, though; can you post your reasoning behind 4000?