distribute	reads
0-500	980053
500-800	341614
800-1000	127821
1000-1200	91940
1200-1400	69451
1400-1600	55740
1600-1800	46289
1800-2000	38942
2000-2200	33989
2200-2400	30084
2400-2600	26981
2600-2800	24612
2800-3000	22337
>3000	655240
