RANK OBSERVED EXPECTED (O-E)^2/E SUM

r<=28 1424 211.4 6954.730 6954.730
r=29 15444 5134.0 20704.258 27658.988
r=30 23132 23103.0 0.036 27659.024
r=31 0 11551.5 11551.524 39210.548

chi-square = 39210.548 with df = 3; p-value = 0.000