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.
[187.583, 187.194, 223.406, 180.269, -57.343, -89.516, 109.096, 167.103, 21.659]