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.
[111.39, 91.315, 18.803, -0.806, 157.023, 191.89, 32.274]