title: Creating an index bar chart in Highcharter
body: <p>I'm trying to create a bar chart showing Cost of Living indexed to the U.S. value (100) in the Highcharter package in R. So I want the bars the start at 100 and either extend to the right or the left of 100. I have the basic bar chart down, but I can't figure out how to move the center line of the chart to 100. I'm trying to get it to look something like this: <a href="http://drawingwithnumbers.artisart.org/moving-the-center-line-of-a-bar-chart-with-a-gantt-chart/" rel="nofollow noreferrer">http://drawingwithnumbers.artisart.org/moving-the-center-line-of-a-bar-chart-with-a-gantt-chart/</a></p>
  
  <p>Here's the data I'm working with:</p>
  
  <pre><code>States &lt;- c('Tennessee','Michigan','Indiana','Ohio','Kentucky','West Virginia','North Carolina','Virginia','Pennsylvania','Delaware','New Jersey','Maryland','New York')
  Cost_of_Living &lt;- c(88.7,88.9,90,90.8,90.9,91.1,94.9,100.7,101.7,108.1,125.1,129.7,139.1)
  costliving &lt;- data.frame(States, Cost_of_Living)
  </code></pre>
  
  <p>And here's the code I have for the bar chart, just the basic bar chart</p>
  
  <pre><code>costliving_graph &lt;- highchart() %&gt;% 
    hc_title(text = "Cost of Living by State (2020)") %&gt;%
    hc_add_series (costliving, "bar", hcaes(x = States, y = Cost_of_Living)) %&gt;%
    hc_xAxis(categories = costliving$States) %&gt;%
    hc_yAxis(title = list(text = "Indexed to the U.S. (U.S. Value = 100)"))%&gt;%
    hc_plotOptions (bar = list(colorByPoint = TRUE)) %&gt;%
    hc_legend (enabled = FALSE)%&gt;%
    hc_tooltip(pointFormat = "MSA Regional Price Parities: {point.y}", headerFormat ="")
  costliving_graph
  </code></pre>
  
  <p>Any help would be great! Thanks in advance</p>