My apologies guys as I've used the incorrect CN to issued ratio.
Here's the revised numbers:
For 2500 visa quota, with 1150/1060/700 left, it will stop at 12152,11745,10438 at 150/160/200 per thousand.
We will need 1383/1360/1123 cases to fill 1150/1060/700 visas.
For 2000 visa quota, with 650/560/200 left, it will stop at 10767,10438,9358 at 150/160/200 per thousand.We will need 782/718/320 cases to fill 650/560/200 visas.
So how do I arrive at those numbers? Let's take 150 per thousand for example.
We have 536 ROA case in the 1st 4300 CN Range, 150 per thousand *4.3/536 = 1.203358 visa per 1 case
Between 9000-10000, we have 296 cases, so we can expect 296*1.203358 visa per 1 case = 356.194 visas
Let's say ROA will take 2500 visa in total, after 9000, we have 2500-(150*9) = 1150
So the question is how many cases do we need to get 1150 visas?
It's 1150/1.203358 visa per 1 case = 955.6589 cases.
If we go to the ceac data on Jan 1, the 955th case after 9000 is CN 12152.
We are assuming every case will respond, which is not true, so you can expect at 80% response rate, the CN will be higher, and even higher for 60% response rate.