distribute	reads
0-500	111981
500-800	153084
800-1000	104569
1000-1200	103795
1200-1400	102303
1400-1600	99980
1600-1800	98266
1800-2000	96839
2000-2200	95301
2200-2400	94225
2400-2600	91963
2600-2800	90220
2800-3000	87921
>3000	2940990
