I noticed the discrepancy in data reported for number of applications. I think that there is a difference between completed applications and total applications (reported to the board).
With regard to the 7.9 million in aid for the 307 spots. The $19.5M is the total for enrolled students over all 4 years but the $7.9M is what was awarded to preps through seniors. Not sure about PGs. So it is not $7.9 times 4 years. Also, this is what is offerred. It is possible that some people offered FA decline it and go somewhere else.
It is also possible that Exeter is being more generous this year compared to prior years.