Definition: 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.
Input: [-12.636, 107.17, 200.315, 67.156, 28.809, 241.797, 197.193, 81.53, -90.008]

91.258