title: How to change the y axis to display percent (%) in Python Plotnine barplot?
body: <p>How can we change y axis to percent, instead of a fraction using Plotnine library in Python?</p>
  
  <p>A MWE of a barplot is as follows:</p>
  
  <pre><code>from plotnine import *
  from plotnine.data import mpg
  
  p = ggplot(mpg) + geom_bar(aes(x='manufacturer', fill='class'), position='fill')
  print(p)
  </code></pre>
  
  <p>Which gives the following figure:</p>
  
  <p><a href="https://i.stack.imgur.com/wwx4M.png" rel="noreferrer">Stacked bar chart with y axis as fraction not percent</a></p>
  
  <p>With ggplot2 in R it is simple, just need to add:</p>
  
  <pre><code>+ scale_y_continuous(labels = scales::percent)
  </code></pre>
  
  <p>However I have not been able to find how to do this in Plotnine. </p>
  
  <p>Any advise?</p>