>>> from pensions import expense_average

>>> l = [['1111A', 68, 640, 589, 573],
...     ['2222D', 69, 710, 550, 570, 698, 645, 512],
...     ['3333J', 72, 530, 534],
...     ['4444N', 75, 770, 645, 630, 650, 590, 481, 602]]
>>> l2 = expense_average(l)
>>> for e in l2:
...   print(round(e, 2))
532.0
600.67
614.17
624.0