This chart isn't really helpful to anyone else. This chart is just straight up gloating about reaching an awesome milestone.
In my last royalty statement, half of my earnings came from my backlist. I completely overwhelmed myself in 2014, and didn't get most of what I wanted done, but my backlist sales are still steady enough to make my royalty check something to look forward too, and a new release still gives things a bump.
Keep writing every body. The only way to do it is to do it!