DRV_COMPA_RATIO is a derived field which is calculated as the actual range as a percentage of the 'Midpoint' amount.
For Example: Employee Wage Rate / Midpoint X 100%
If the midpoint salary is $40,000 and the employees wage rate is:
$20,000, then compa ratio would be 50%
$40,000, then compa ratio would be 100%
$60,000 then compa ratio would be 150%