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

r<=28 217 211.4 0.147 0.147
r=29 5056 5134.0 1.185 1.333
r=30 23245 23103.0 0.872 2.205
r=31 11482 11551.5 0.418 2.623

chi-square = 2.623 with df = 3; p-value = 0.453