A radial chart of USA airlines on-time performance.

Things have done:

• Used a cleaner way to transform the chart to center
• Learned how to close the line: using d3.curveLinearClosed

Things to do:

• Using a cleaner way to choose the range for radiusScale, for now just manually select [180, innerHeight/2]
• Choosing a range for the angle scale that represents some periodic amount of time, like years, months, or weeks.
• Adding axes (tick marks and labels) for angle
• Adding axes (tick marks and labels) for radius