1968
 JanFebMarAprMayJunJulAugSepOctNovDec
1 1 --- --- --- 1 1 --- --- 1 1 1 ---
2 --- --- --- 1 1 1 --- --- --- 1 1 ---
3 --- 1 --- --- 1 1 1 1 1 --- 1 1
4 --- 1 --- --- 1 --- 1 1 1 --- 1 ---
5 --- 1 --- 1 1 1 1 --- 1 1 1 ---
6 --- 1 --- 1 1 1 1 --- --- --- 1 1
7 --- --- --- 1 1 1 1 1 1 1 1 ---
8 --- --- --- 1 1 1 1 1 --- 1 1 ---
9 --- --- 1 1 1 1 1 1 1 1 --- ---
10 1 --- --- --- 1 1 1 1 --- 1 --- ---
11 --- --- --- 1 1 1 1 1 1 --- 1 1
12 --- --- --- 1 1 1 1 1 1 --- 1 1
13 --- --- --- 1 1 1 1 1 1 1 1 1
14 --- --- --- 1 1 1 1 --- 1 --- --- 1
15 --- --- --- 1 1 1 1 1 1 1 1 1
16 --- 1 1 1 1 1 1 1 1 --- --- 1
17 --- --- 1 1 --- 1 1 1 1 --- --- ---
18 --- --- 1 1 --- --- 1 1 1 --- --- ---
19 --- --- 1 1 --- 1 1 1 1 1 1 1
20 1 --- 1 1 --- 1 --- 1 1 --- --- ---
21 --- --- 1 --- 1 1 1 --- --- 1 --- 1
22 --- --- 1 1 1 1 1 --- --- 1 --- 1
23 --- --- 1 1 1 1 1 1 1 1 --- 1
24 --- --- --- 1 1 1 1 1 1 1 --- 1
25 1 --- 1 1 1 1 1 1 --- 1 --- 1
26 1 --- 1 1 1 1 1 1 --- 1 --- ---
27 1 --- 1 1 1 --- 1 1 --- 1 --- ---
28 --- --- 1 1 1 1 1 1 --- 1 --- ---
29 --- --- 1 1 1 1 1 1 --- 1 1 1
30 1   1 1 1 --- --- 1 1 1 --- ---
31 ---   1   1   --- 1   1   1