# Sharpe Ratio for loans

I am trying to calculate the sharpe ratio for a set of loans. These loans have already matured and I know if they were good or not: grades are the different grades of the loans. interest rate is the floating point value:

12.12
13.11
7.90
8.90
15.31
14.33
11.14
16.29
17.27
10.99


this is the python code that tries to compute the sharpe ratio for each grade.

for grade,name in enumerate(grades):