title: How to access variable in the nested list and plot histogram
body: <p>I have data below:</p>
  
  <pre><code>[{'_id': {'day': 11, 'month': 10, 'site_id': '3146102', 'year': 2015}, 'totalVolume': 15731.74},
  
  {'_id': {'day': 1, 'month': 10, 'site_id': '3146102', 'year': 2018},
    'totalVolume': 70537522.867},
  
  {'_id': {'day': 30, 'month': 9, 'site_id': '3146102', 'year': 2018},
    'totalVolume': 293037881.211}]
  </code></pre>
  
  <p>How to access <code>month</code> and plot total volume based on <code>month</code>? </p>