Hi I have a dataframe that I'd like to select the column with the highest percentage from a frequency table.

```
d = {'c1':['a', 'a', 'b', 'b', 'c', 'c'], 'c2':['Low', 'High', 'Low', 'High', 'High', 'High']}
dd = pd.DataFrame(data=d)
dd.groupby('c1')['c2'].value_counts(normalize=True).mul(100)

```

It will return a frequency table

```
c1  c2  
a   High     50.0
    Low      50.0
b   High     50.0
    Low      50.0
c   High    100.0
Name: c2, dtype: float64

```

I'd like to print out `c` which has the highest percentage `100.0`

I'm able to use `max()` to print out `100.0` but don't know how to print out `c`