Current items in legend are:

• Total Estimate
• Complete Estimated Issues
• Total number of issues
• Total number of unestimated issues

We think this is not clear in terms of relating the legend items to the specific y-axis on the chart. Also "Complete Estimated Issues" makes me think "issue count" rather than "Story Points" as the unit of measurement.

Our suggestion:

• Total Story Points (substitute Story Points for the estimation statistic)
• Completed Story Points
• Number of issues
• Number of unestimated issues