title: Pandas get frequency of item occurrences in a column as percentage
body: <p>I want to get a percentage of a particular value in a df column. Say I have a df with (col1, col2 , col3, gender)  gender column has values of M, F, or Other. I want to get the percentage of M, F, Other values in the df.</p>
  <p>I have tried this, which gives me the number M, F, Other instances, but I want these as a percentage of the total number of values in the df.</p>
  <pre><code>df.groupby('gender').size()
  </code></pre>
  <p>Can someone help?</p>