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

r<=28 234 211.4 2.412 2.412
r=29 5239 5134.0 2.147 4.559
r=30 23117 23103.0 0.008 4.567
r=31 11410 11551.5 1.734 6.301

chi-square = 6.301 with df = 3; p-value = 0.098