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.
[-25.521, 195.926, 77.241, 19.481, 25.586, 199.048, 149.617]