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.
[-17.109, -54.795, -63.623, 199.981, 80.396, 45.601, 112.538, 212.129]