title: Excel - Add a single horizontal "target line" to the horizontal axis
body: <p>I have a X Y (Scatter) chart in Excel that is currently displaying two data sets exactly as I want them. Is it possible to add a single "target" line at a point of my choosing across the X access?</p>
  
  <p>So let's say the Y axis is 0% up to 100%. let's say I am only ever happy if either line that I have plotted are below 50%. Is it possible to add a single red line, across 50%, so I can see at a glance when a line is on or below it? </p>