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: [-59.098, -22.489]
Example Output: -40.794

Example Input: [199.728, -96.25, -77.714]
Example Output: 8.588

Example Input: [195.64, 22.532, -32.619, 249.056, -93.903, -27.887, 55.242]
Example Output:
52.58