PDF Pages matplotlib

import pandas
import matplotlib
import matplotlib.pyplot as plt
from matplotlib.backends.backend_pdf import PdfPages


matplotlib.style.use('ggplot')

df = pandas.read_excel('results.xls')
df.set_index("Candidate Number", inplace=True)

df['Overall'] = df.mean(axis=1)
# print(df.head())

pp = PdfPages('results.pdf')

for col in df:
    figure = df[col].plot(
        bins=list(range(0, 101, 10)),
        kind='hist',
        legend=True,)
    pp.savefig()
    plt.clf()

pp.close()