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.
[14.211, -10.736, -78.368, 5.847, 197.61, 102.038, 221.906, -16.19, 183.615]