Number of measurements available in each month during the year of 1997-2002
Month
1997
1998
1999
2000
2001
2002
1
0
0
0
0
11
10
2
0
0
0
6
9
7
3
0
0
0
7
10
7
4
0
0
0
9
10
9
5
0
0
0
5
11
10
6
0
0
0
6
10
9
7
0
0
0
9
10
11
8
0
0
0
9
10
10
9
0
0
0
10
10
9
10
0
0
0
10
11
10
11
0
0
0
10
10
10
12
0
0
0
10
10
11