title: How to sort multiple columns in Python?
body: <p>I have a sample dataframe as below.</p>
  <pre><code>d={
      'Country' :['Bermuda','Australia','Switzerland','Norway','Iceland','United Kingdom','Denmark'],
      '1960':[231,3424,4354,857,644,2355,743],
      '1970':[8674,4364,564,7563,868,742,55],
      '1980':[44,5456,34556,34254,565,568,97],
      '1990':[23234,556,34,5656,67,89765,45],
      '2000':[343,6767,356,5657,324345,4566,346]
  }
  
  df=pd.DataFrame(d, columns=['Country','1960','1970','1980','1990','2000'])
  </code></pre>
  <p>It looks like this:</p>
  <p><a href="https://i.stack.imgur.com/iNn1C.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/iNn1C.png" alt="enter image description here" /></a></p>
  <p>I want to show top-4 countries which have the highest values for each year as a result.</p>
  <p>Expected results:</p>
  <p><a href="https://i.stack.imgur.com/tSwiZ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/tSwiZ.png" alt="enter image description here" /></a></p>