using maximum likelihood fit a Poisson distribution to the
following famous data on the number of deaths from the kick of a
horse per army corps per year, for 10 Prussian Army corps for 20
years. The total number of units here, an army corps per year, is
n=200.
# of deaths from horse kick: 0 1 2 3 4
Observed frequency: 109 65 22 3 1