distribute	reads
0-500	3119
500-800	2483
800-1000	1724
1000-1200	1985
1200-1400	2659
1400-1600	4127
1600-1800	6535
1800-2000	10130
2000-2200	14654
2200-2400	19979
2400-2600	24730
2600-2800	29049
2800-3000	32279
>3000	303461
