distribute	reads
0-500	2436
500-800	2986
800-1000	2468
1000-1200	3070
1200-1400	4389
1400-1600	6500
1600-1800	9989
1800-2000	13569
2000-2200	15800
2200-2400	14423
2400-2600	11460
2600-2800	9149
2800-3000	7287
>3000	26348
