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

r<=28 234 211.4 2.412 2.412
r=29 5156 5134.0 0.094 2.506
r=30 23103 23103.0 0.000 2.506
r=31 11507 11551.5 0.172 2.678

chi-square = 2.678 with df = 3; p-value = 0.444