I need to calculate the rate of infection per patient from a report. This report returns the number of months the patient had a catheter and the number of infections they had during this time.

What i need to do is add a column at the end that displays the infection rate per patient. For example, if a patient has had a catheter in for 12 month and they have had 2 infections, the rate is 2:12 or 1:6.

How do i create this in Crystal Reports? Not used it much so learning.

Cheers,

Mike D

Edit: The data is from a MySQL database that holds all patient information. I extracted the date that the catheter was inserted as well as the date it was removed and the nunber of infections the patient had during this time. I then used MySQL to calculate the number of months it was in from those two fields.
No I need to calculate (with MySQL or Crystal) the rate of infection per month.

For example, a patient has a catheter for 12 months and has 2 infections, the rate is 2:12 or 1:6.

I hope this is clearer.