%d not working in re at Python 2.7?

[vacu]

I am frustrated to see %d not working in my Python 2.7 re.search, like
this example:

>>> (re.search('%d', "asdfdsf78asdfdf")).group(0)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'NoneType' object has no attribute 'group'


\d works fine:

>>> (re.search('\d+', "asdfdsf78asdfdf")).group(0)
'78'


And google search ignores % in their search, so I failed to find
answer from Python mailing list or web,
Do you have any idea what's problem here?

Thanks a head
Vacu