Formatting issues?

[Mark17]

Here's some code:

format_mapping2 = {'ES_Cum_%ROI':'{:.2%}','Port_Cum_%ROI':'{:.2%}','Port_Marg_Tot':'{:.2f}'}
for key, value in format_mapping2.items():
    comp_df[key] = comp_df[key].apply(value.format)
print(comp_df)
comp_df = comp_df.apply(pd.to_numeric)
print(comp_df.dtypes)
ES_mean = comp_df.iloc[:,0].mean()

With lines 1-3, comp_df prints with the formatting I want.

I then want to do further processing, though... like get mean, std, min/max, etc. When I include the last line, I get: ValueError: Unable to parse string "276.50%" at position 0 . If I take out line 5, then I get TypeError: Could not convert 272.31%165.15% to numeric (that's why I tried WITH line 5).

So--when I format these columns as percentages, am I actually changing them to strings (with or without lines 1-3, dtypes show up as "object" for all columns)? And if they are strings, how to I change them back to numeric so I can proceed with the further processing? Thanks!