Rate: noun
1. a measure, quantity, or frequency, typically one measured against some other quantity or measure.
"the crime rate rose by 26 percent"

So:

The Literacy *Rate* would be a level of literacy against the total. So, if, of 100 individuals 12 are able to read and write at a college level, that Literacy Rate would be 12%. If that Rate changes year-on-year, the Rate would change by some percentage measured against the former year, and against whatever baseline is used - year 1, if you will.

Peter Wieck
Melrose Park, PA