distribute	reads
0-500	277729
500-800	86125
800-1000	29193
1000-1200	19545
1200-1400	13662
1400-1600	9503
1600-1800	7349
1800-2000	5754
2000-2200	4486
2200-2400	3761
2400-2600	3036
2600-2800	2638
2800-3000	2364
>3000	38956
