Section C9 of the Common Data Set reports how many enrolled first-years sent an SAT and how many sent an ACT. A student who sent both is counted twice, so C9 cannot give the exact share who sent neither.
The table therefore shows the guaranteed minimum, which is 100% minus SAT senders minus ACT senders. The true share cannot be lower. Where a school publishes an exact figure for the same class, that figure replaces the minimum and is marked exact.
Twelve schools publish both. At eleven of them the exact figure sits 0 to 2 points above the minimum. At Harvey Mudd it is 6 points above, because so many students send both tests. Read every minimum as roughly one to two points low.
The six University of California campuses are shown at 100% because scores play no part in their admission decisions.
The top 60 national universities run to 68 schools because ten tie at 59th. The liberal arts list ends at a four-way tie for 22nd, which makes exactly 25.