How would anyone know what percentage of greyhounds went where if the NGA won't even record this information and share it with the public? Do we just wait until jcsperson deems it so with unverifiable "estimates"?

Greyhounds are not registered until they are 1 1/2 years old. Your numbers don't even begin with the actual number whelped.
We have seen adult greyhounds who went into adoption that were never registered at all.

Florida has the largest concentration of greyhounds in the country. According to the adoption people there who work in the trenches, they are not able to take even half of the greyhounds needing to go into adoption each year. What do you suppose those "caring owners" do with the all their dogs?

Jay