title: get the bars in barplot to have the same height
body: <p>How do I get the bars in my barplot to have the same height?</p>
  
  <pre><code>&gt; head(data.m)
    Classes variable        value
  1    rRNA  KO1.DOC 4.890821e+04
  2    rRNA  KO1.DOC 3.068479e+03
  3   Other  KO1.DOC 7.618553e+01
  4   Other  KO1.DOC 4.043281e-01
  5   Other  KO1.DOC 0.000000e+00
  6   Other  KO1.DOC 0.000000e+00
  
  ggplot(data.m, aes(variable, fill=Classes, order = -as.numeric(Classes))) +
    geom_bar(aes(y=value), position="stack", stat="identity") + 
    theme_bw(base_size=8)
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/Ny30m.png" alt="enter image description here"></p>