Converting monthly data into average daily data

Hi,

I have a set of production data where there is a monthly fluid rate paired with a corresponding date, in the form mm/dd/yyyy. What I would like to do is convert the monthly data into an average daily rate by simply dividing by 30.4 to approximate this value. However, the data set I have has >30 different entities, so I was wondering if there was a quick way to be able to convert monthly rates into an average daily rate without having to go through the painstaking process of converting each individual month and spreading the value across 30-day increments month by month manually, then repeating the process 30+ times for every other entity in my db. Any tips would be greatly appreciated. Thank you!

Ex:
Name Date Rate per Month
Well 1 1/1/2011
Well 1 2/1/2011
Well1 3/1/2011
Well 2 3/1/2012
Well 2 4/1/2012
Well2 5/1/2012
Well 3 2/1/2009