distribute	reads
0-500	270408
500-800	5499
800-1000	228
1000-1200	78
1200-1400	31
1400-1600	8
1600-1800	10
1800-2000	7
2000-2200	4
2200-2400	1
2400-2600	1
2600-2800	1
2800-3000	1
>3000	1
