I have thousand of rows in excel and I need to average the 2 preceding rows every time a zero is found. For example

```
Column1
23
12
0
32
10
0
```

I need the average of 23 and 12 to replace the zero found in the third row. As well as the average of 32 and 10 to replace the zero found in the sixth row. Any help would be much appreciated!