In order for the number of families to go from 12,000 to 20,000 in 7 years, there would have to be 8,000 new families each year. That comes out to 95 a month. That would mean that each month, there are a total of 95 couples getting married and moving to/staying in Lakewood as well as families moving to Lakewood.
I think that as of a few years ago, there were at least 500 12th grade girls in Lakewood. That should mean that on average, there are 500 Lakewood girls getting married a year. Even if we assumed that the Nasi people are correct and only 90% of girls get married, that is still 450. That is 37.5 a month, the vast majority of whom stay in Lakewood.
Then we have to add in all of the girls who are not from Lakewood but move there after they get married. I would guess that that is a greater number. So let’s say that is another 50-70 girls.
We then have to add in all the families moving to Lakewood each year.
So it does seem that 95 a month is quite possible.
Now, this was just based on guestimation. And since I am not a statician or a sociologist, there may be many errors here. Feel free to point them out.