我正在从熊猫数据读取器查询AAPL数据。我指定的日期为1991-1-1，但是如果您查看我收到的数据，则该日期为89-01-03。
import pandas as pd
from pandas import datetime
from pandas import DataFrame as df
import matplotlib
from pandas_datareader import data as web
data = web.DataReader("AAPl", 'yahoo', 1991-1-1, 2019-1-10)
data.index = pd.to_datetime(data.index, format ='%Y-%m-%d')
数据：
High Low Open Close Volume Adj Close
Date
1989-01-03 1.446429 1.428571 1.437500 1.441964 25004000.0 1.164242
1989-01-04 1.504464 1.446429 1.455357 1.500000 59987200.0 1.211100
1989-01-05 1.544643 1.473214 1.500000 1.508929 76832000.0 1.218310
1989-01-06 1.553571 1.508929 1.508929 1.522321 49666400.0 1.229123
1989-01-09 1.540179 1.508929 1.535714 1.535714 19826800.0 1.239936
... ... ... ... ... ... ...
2007-12-24 28.475714 27.827143 27.861429 28.400000 120050700.0 24.785059
2007-12-26 28.708570 28.117144 28.430000 28.421429 175933100.0 24.803761
2007-12-27 28.994286 28.257143 28.421429 28.367144 198881900.0 24.756376
2007-12-28 28.794285 28.125713 28.655714 28.547142 174911800.0 24.913471
2007-12-31 28.642857 28.250000 28.500000 28.297142 134833300.0 24.695290
4790 rows × 6 columns
为什么我要从另一个日期开始获取数据？