Problem: A program for patrolling a U.S region for illicit activities using aircraft is being assessed. An associated estimate of the total economic benefits of the interdiction vs. the number of patrol aircraft is shown below. Apply the first fundamental proposition of marginal reasoning to determine the optimal number of patrol aircraft.
# Patrol Aircraft Benefit ($M)
1-> 1995
2-> 3458
3-> 4522
4-> 5320
5-> 5852
6-> 6155
7-> 6358
8-> 6517
9-> 6610
10-> 6677