I believe the way it is in the DB is a cold hard number.... The formula is decided by the coding (I believe, could be wrong on that) will have to research when I get home also...
So, yes, you can change the rate of exp or single AND for group in the variables table, but I dont know the formula that this changes... Either ask this question in EQEMu developement forum, or just experiment with the numbers...
Hope that helps at least SOME...