import pandas

binwidth = 10
data = pandas.read_csv('sample.csv', sep=' ', names=['time', 'value'], header=None, comment='#')

mylist = []

for item in data.iterrows():
    index = item[1]['time']/binwidth
    if len(mylist) <= index:
        mylist.append(1)
    else:
        mylist[index] += 1

print mylist # [8, 4, 4]

# time value
1 a
2 b
3 c
4 d
6 e
7 f
8 g
9 h
10 i
12 j
15 k
17 l
21 m
22 n
26 o
29 p