title: How to extract only cetain part of a column
body: <p>I have a dataframe that looks like below.I want to keep only first percentage from column 3 and 4. How can this be achieved.Any help is appreciated</p>
  <pre><code>Metric Group  Metric Type       Tue23rd                      Week24                      
  Productive    % Available     83.2%Best Class:D7-92.6%     92.6%Best Class:WD-96.21%
  Productive    % Available     85.2%Best Class:A7-98.6%     92.6%Best Class:LD-95.21%
  Productive    % Available     89.2%Best Class:D7-94.6%     92.6%Best Class:WD-93.21%   
  </code></pre>
  <p>Expected output is some thing like</p>
  <pre><code>Metric Group    Metric Type       Tue23rd          Week24                      
  Productive     % Available        83.2%             92.6%
  Productive     % Available        85.2%             92.6%
  Productive     % Available        89.2%             92.6%      
  </code></pre>