Wrong caption (unit) in change/mean.svg

[hmeine]

I have just started really working with criterion productively, and I am using 0.5.1, so apologies if this has been noticed and was fixed in the latest development version – I only checked for issues and did not dive into the sources.

I noticed that the relative changes are captioned to be in percent, but they really are not:

For instance, it makes a difference when seeing that the change is around 0.1 ("%"), which would be insignificant in my case, but the report reveals that this is really a fraction of 0.1, so 10%!

I do not have gnuplot installed on the relevant system, so this is apparently using plotters, in case that matters (and is not obvious just from the SVG).