In this task you will be given a list of numbers and you need to find the mean (average) of that list. The mean of a list can be found by summing every number in the list then dividing the result by the size of that list. The output should be rounded to 3 decimal places.

Example Input: [-8.87, 232.908, 141.714, -47.559, 161.192, 203.441]
Example Output: 113.804

Example Input: [22.971, 146.947, 84.327, 123.65, -30.682, -43.973, 211.836, 146.398, -65.992]
Example Output: 66.165

Example Input: [-59.938, 12.276]
Example Output:
-23.831