title: Is there unexpected number result for Counter.most_common
body: <pre><code>from collections import Counter
  
  # Frequency table for a list of numbers
  def frequency_table(numbers):
      table=Counter(numbers)
      for number in table.most_common():
          print('{0} \t {1}'.format(number[0],number[1]))
          
  if __name__=='__main__':
      scores=[7,8,9,2,10,9,9,9,9,4,5,6,1,5,6,7,8,6,1,10]
      frequency_table(scores)
  </code></pre>
  <p>After I run this, the 2 term turns into twenty  one, I try many times, I put the results below</p>
  <p>9 5<br />
  6 3<br />
  7 2<br />
  8 2<br />
  10 2<br />
  5 2<br />
  1 2<br />
  twenty one<br />
  4 1</p>