I was unsure what the classic 'Years to FIRE' plot was really showing from the MMM article so I rederived it.

http://www.mrmoneymustache.com/2012/01/13/the-shockingly-simple-math-behind-early-retirement/It looks like the original plot showed years to FIRE vs savings rate for given market returns assuming a 4% withdrawal rate.

MatLab source code attached, please let me know if I made any mistakes. I ran it for full years then curve fit it so the lines are a bit wobbly.