1981
 JanFebMarAprMayJunJulAugSepOctNovDec
1 --- --- 1 --- --- 1 1 1 1 1 --- ---
2 --- --- 1 --- --- 1 --- 1 1 --- 1 ---
3 1 --- --- --- 1 1 1 1 1 1 --- ---
4 --- --- --- --- --- 1 1 1 1 1 --- ---
5 --- 1 --- --- 1 1 1 1 --- 1 1 ---
6 --- --- --- --- --- 1 --- 1 1 1 --- ---
7 --- --- --- --- --- 1 1 1 1 1 --- ---
8 --- --- --- --- --- 1 --- 1 1 1 --- ---
9 --- --- 1 --- --- 1 1 1 --- --- --- ---
10 --- 1 1 --- --- 1 1 1 --- --- --- ---
11 --- --- --- 1 1 1 --- 1 1 1 --- ---
12 --- 1 --- 1 --- 1 --- 1 1 1 --- ---
13 --- --- --- 1 --- --- 1 1 --- 1 --- ---
14 --- --- --- 1 --- --- 1 --- --- --- --- ---
15 --- --- 1 1 --- --- 1 1 1 --- 1 ---
16 1 --- --- --- 1 1 1 1 --- --- --- ---
17 --- --- --- --- 1 1 1 1 --- --- --- ---
18 --- --- --- --- 1 1 1 1 1 --- --- ---
19 --- --- --- --- 1 1 1 1 --- 1 1 ---
20 --- --- --- --- 1 1 1 1 1 --- 1 ---
21 --- --- --- --- 1 1 1 1 --- --- --- ---
22 --- 1 1 1 1 1 1 1 1 1 --- ---
23 --- 1 1 1 --- 1 1 1 1 1 --- ---
24 --- --- --- 1 --- 1 1 --- 1 1 --- ---
25 --- 1 1 --- --- 1 1 1 1 1 --- ---
26 --- --- --- --- 1 1 1 --- --- 1 --- ---
27 --- --- 1 1 --- 1 1 --- --- 1 --- ---
28 1 --- --- --- 1 1 1 --- 1 --- --- ---
29 ---   --- --- 1 1 1 --- 1 --- 1 ---
30 1   --- --- 1 1 1 --- 1 --- --- ---
31 ---   ---   1   1 ---   ---   ---