import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.dates as mdates

dates = pd.date_range('20070101',periods=1000)
df = pd.DataFrame(np.random.randn(1000), index = dates, columns =list ('A'))

fig,ax = plt.subplots()
df.plot(x_compat=True,ax=ax)

ax.xaxis.set_tick_params(reset=True)
ax.xaxis.set_major_locator(mdates.YearLocator(1))
ax.xaxis.set_major_formatter(mdates.DateFormatter('%Y'))

plt.show()