How To Calculate Percentage Hike To Be Given To The Employee

Hello,
I am working in an IT company and as a part of the performance appraisal, I need to calculate the percentage hike to be given to the employees as a result of their ratings in the annual appraisal process.We follow a five point rating scale (5=Significantly exceeds expectations, 4=Exceeds expectations,3=Meets expectations,2=Meets most expectations and 1=Below expectations).
Now I need to decide as to what ratings to be assigned to the above mentioned scale (For eg: someone who will get the rating as 3 will be given 8% hike etc)
Please can someone help me with this?
Thanks and regards,
Monicag

Dear,
You have given the rating regarding performance appraisals.
But I dont know the policy of your company regarding P.A.
U can giev the % regarding their rating.
5=Significantly exceeds expectations: 26% to 35%
4=Exceeds expectations:- 19% to 25%
3=Meets expectations: 11%to 18%
2=Meets most expectations :- 5% to 10%
1=Below expectations). : 0%
Its my opinion
regards
RAJNISH SAPRA

Hello Rajnish,
Thanks for your reply. My company follows a simple one to one performance appraisal method.
However one needs to do some background calculation(like market survey,inflation rate etc) in order to reach the percentage slabs that you have mentioned.So my question is that how do you reach these slabs?
Hope I am able to clarify my question this time. Look forward to earliest reply on this as this is pretty urgent.
Thanks and regards,
Monicag