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: [134.631, 27.106]
Example Output: 80.868

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: [244.454, -60.861, 12.995, 143.486, 203.163, 215.813, 72.241, 102.645]
Example Output:
116.742