Antenna signal strength question

The antenna signal strength on my Roamio basic ranges from 58 to 72 on the channels I care about. I have read that 72 is the max reading the Tivo gives (although I have occasionally seen a higher reading on one channel).

A couple questions: if a channel reads 72, does that mean the signal is a strong as it can be? Also, it is a linear scale? IOW, does a 60 reading mean the signal strength is 83% of a 72 reading?

Antenna signal strength question