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

r<=28 235 211.4 2.630 2.630
r=29 5112 5134.0 0.094 2.725
r=30 22995 23103.0 0.505 3.230
r=31 11658 11551.5 0.981 4.212

chi-square = 4.212 with df = 3; p-value = 0.240