title: Passing confidence level to ACF plot
body: <p>I have the following time series data:</p>
  
  <pre><code>x &lt;- ts(c(-3151, -873, 135, 825, 1531, -1420, -282, 
      2113, -916, -2222, -4654, -604, -1322, 
     -15457, 13835, 446, 1402, -1230, 1790, 1374, 1463))
  </code></pre>
  
  <p>By default the autocorrelation function plots lines at 95% confidence:</p>
  
  <pre><code>acf(x)
  </code></pre>
  
  <p>(see blue dashed lines in the picture below)</p>
  
  <p><a href="https://i.stack.imgur.com/8yPGk.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/8yPGk.png" alt="enter image description here"></a></p>
  
  <p>Is there a way to pass in 90% confidence levels to this plot instead of the default 95% levels?  For instance, this does not work</p>
  
  <pre><code>acf(x, level=90)
  </code></pre>