Measure throughput & elements

[vlovich]

Kind of did it in reverse & opened #722 already before checking the contribution readme.

Basically, I am doing data processing where I have both a number of elements & each element has a size. Larger elements may increase throughput but decrease the elements/s while smaller elements have the reverse effect. I've wanted the ability to ask for the reporting infrastructure to show both simultaneously. MVP is the text summary. HTML support would be nice but out of scope for the MVP IMO.