`groupby.size()` should have the ability to "normalize" the results and return them as a percentage. ``` df['col'].value_counts(normalize=True) A = 0.25 B = 0.25 C = 0.25 D = 0.25 ``` To accomplish this result with a `groupby.size()` you have to do the following - ``` df2 = df.groupby(['subset_product', 'subset_close']).size().reset_index(name='prod_count') a = df2.groupby('subset_product')['prod_count'].transform('sum') df2['prod_count'] = df2['prod_count'].div(a) ``` Is there a way to add a feature to include this as a parameter in `.size()`