I would like to create a row in the bottom of a dataframe which counts the number of occurences of a given number (0 in this case) appears in each column

```
df = pd.DataFrame({'Bread':[1,"Nan",3.3, 0],
           'Butter': [2, 3, "Nan", 1],
           'Jam': [0, 0, 0.3, 0.7]})

print (df)
Bread Butter  Jam
0     1      2  0.0
1   Nan      3  0.0
2   3.3    Nan  0.3
3     0      1  0.7

```

My expected outcome would be (with additional row "Occ")

```
print (df)
    Bread Butter  Jam
    0     1      2  0.0
    1   Nan      3  0.0
    2   3.3    Nan  0.3
    3     0      1  0.7
   Occ   1      0    2

```