title: How to fill area under line plot in seaborn
body: <p>I want to fill the area under a line plot so it looks as the picture below:
  <a href="https://i.stack.imgur.com/yHWwM.png" rel="noreferrer"><img src="https://i.stack.imgur.com/yHWwM.png" alt="it should look like it"></a></p>
  
  <p>instead of </p>
  
  <p><a href="https://i.stack.imgur.com/sU8nb.png" rel="noreferrer"><img src="https://i.stack.imgur.com/sU8nb.png" alt="enter image description here"></a></p>
  
  <p>built on the following .csv file:</p>
  
  <pre><code>01-01-97    1
  01-02-97    2
  01-03-97    3
       ...
  01-11-17    251
  01-12-17    252
  01-01-18    253
  </code></pre>
  
  <p>what should I change in this code to generate the desired graph?</p>
  
  <pre><code>import pandas as pd
  import seaborn as sns
  from matplotlib import pyplot as plt
  
  # load csv
  df=pd.read_csv("test.csv")
  # generate graph
  g = sns.lineplot(x="Date", y="Data", data=df)
  
  plt.show()
  </code></pre>