distribute	reads
0-500	141849
500-800	15566
800-1000	1045
1000-1200	241
1200-1400	87
1400-1600	32
1600-1800	18
1800-2000	10
2000-2200	5
2200-2400	3
2400-2600	1
2600-2800	4
2800-3000	3
>3000	28
