我有以下代码：

import pandas as pd
DF = pd.DataFrame({
    "item_id": [1, 2, 3, 4, 5, 6, 7, 8, 9],
    "custumer": ["CG", "CGD", "CC", "CZ", "JD", "KD", "MM", "MK", "JJ"],
    "costs": [150, 12, 78, 56, 5, 6, 4, 68, 69],
    "games": [["Minecraft", "Uno"], ["WOW", "Minecraft"], ["WOW", "Minecraft"], ["WOW", "Minecraft", "The last of us"], ["Monopoly"], ["Monopoly", "Uno"], ["WOW", "Monopoly"], ["Uno", "SkipBo"], ["Schach", "Uno"]], 
    "date": ["2022-01-18", "2022-03-12", "2022-02-26", "2021-11-12", "2021-10-09", "2021-11-26", "2021-10-18", "2021-12-22", "2021-09-06"]
})

DF["games"] = [i[-1:] for i in DF["games"]]
DF["Day"] = pd.to_datetime(DF["date"]).dt.day
DF["Month"] = pd.to_datetime(DF["date"]).dt.month
DF["Year"] = pd.to_datetime(DF["date"]).dt.year
DF #(look at pic_1)

newDF_month = DF.drop(columns=["item_id", "custumer", "games", "date", "Day", "Year"])
newDF_month.groupby(["Month"]).sum()

但是，这表示使用排序（1，2，3，9，10，11，12）按月排序的数据：

month | costs
-------------
   1  | 150
   2  |  78
   3  |  12
   9  |  69
  10  |   9
  11  |  62
  12  |  68

但我想让排序为（9，10，11，12，1，2，3）：

month | costs
-------------
   9  |  69
  10  |   9
  11  |  62
  12  |  68
   1  | 150
   2  |  78
   3  |  12

我该怎么做？