title: Pandas sort_values does not sort numbers correctly
body: <p>I'm new to pandas and working with tabular data in a programming environment. I have sorted a dataframe by a specific column but the answer that panda spits out is not exactly correct.</p>
  
  <p>Here is the code I have used:</p>
  
  <pre><code>league_dataframe.sort_values('overall_league_position')
  </code></pre>
  
  <p>The result that the sort method yields values in column 'overall league position' are not sorted in ascending or order which is the default for the method.</p>
  
  <p><a href="https://i.stack.imgur.com/19R4Z.png" rel="noreferrer"><img src="https://i.stack.imgur.com/19R4Z.png" alt="enter image description here"></a></p>
  
  <p>What am I doing wrong? Thanks for your patience!</p>