如何用pandas绘制具有不同值但比例相同的列？

import pandas as pd
import matplotlib.pyplot as plt

data = {'Column1': [1, 2, 3, 4, 5],
        'Column2': [1, 2, 3, 4, 5],
        'Column3': [1, 2, 3, 4, 5]}
df = pd.DataFrame(data)

df.plot(kind='bar')
plt.show()