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: [-90.211, -60.08, 99.87, 18.704, 197.269, 173.722, 168.875]
Example Output: 72.593

Example Input: [-46.14, -0.077, 72.663, 81.035, -24.144, 66.514, 98.199]
Example Output: 35.436

Example Input: [22.894, 154.361, -77.253, 196.073]
Example Output:
74.019