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

r<=28 197 211.4 0.983 0.983
r=29 5211 5134.0 1.155 2.138
r=30 23110 23103.0 0.002 2.140
r=31 11482 11551.5 0.418 2.558

chi-square = 2.558 with df = 3; p-value = 0.465