在python2.7.11中 import matplotlib.pyplot as plt 出现下面错误，请大神帮忙看看怎么解决！

>>> import matplotlib
>>> import matplotlib.pyplot as plt
RuntimeError: module compiled against API version 9 but this version of numpy is 6

Traceback (most recent call last):
  File "<pyshell#8>", line 1, in <module>
    import matplotlib.pyplot as plt
  File "D:\Program Files\python2.7\lib\site-packages\matplotlib\pyplot.py", line 29, in <module>
    import matplotlib.colorbar
  File "D:\Program Files\python2.7\lib\site-packages\matplotlib\colorbar.py", line 32, in <module>
    import matplotlib.artist as martist
  File "D:\Program Files\python2.7\lib\site-packages\matplotlib\artist.py", line 14, in <module>
    from .transforms import (Bbox, IdentityTransform, TransformedBbox,
  File "D:\Program Files\python2.7\lib\site-packages\matplotlib\transforms.py", line 39, in <module>
    from matplotlib._path import (affine_transform, count_bboxes_overlapping_bbox,
ImportError: numpy.core.multiarray failed to import