distribute	reads
0-500	652245
500-800	322593
800-1000	121921
1000-1200	85874
1200-1400	63094
1400-1600	48547
1600-1800	38223
1800-2000	30429
2000-2200	25650
2200-2400	21432
2400-2600	18152
2600-2800	16620
2800-3000	13585
>3000	135158
