Pandas Groupby를 사용하여 각 주 내 사무실당 매출 비율을 계산하는 방법은 무엇입니까?

import pandas as pd

df = pd.DataFrame({'state': ['CA', 'WA', 'CO', 'AZ'] * 3,
                   'office_id': list(range(1, 7)) * 2,
                   'sales': [np.random.randint(100000, 999999)
                             for _ in range(12)]})

state_office = df.groupby(['state', 'office_id']).agg({'sales': 'sum'})

state_pcts = state_office.groupby(level=0).apply(lambda x:
                                                 100 * x / float(x.sum()))

print(state_pcts)
                     sales
state office_id           
AZ    2          16.981365
      4          19.250033
      6          63.768601
CA    1          19.331879
      3          33.858747
      5          46.809373
CO    1          36.851857
      3          19.874290
      5          43.273852
WA    2          34.707233
      4          35.511259
      6          29.781508