distribute	reads
0-500	2767383
500-800	772666
800-1000	259021
1000-1200	166975
1200-1400	114030
1400-1600	82533
1600-1800	61764
1800-2000	47655
2000-2200	37936
2200-2400	30625
2400-2600	25596
2600-2800	21105
2800-3000	18327
>3000	198161
