what you need is some kind of control on the numbers.
if you can take a group where all (Z) species are known for the last (X) years and during that time there have been (Y) speciation events
then you can say for this group you get Y/X/Z speciation events per year per species
you could also graph it against time and work out a standard distribution of events over time
but if you run the same parameters on another group you will get different results
and this doesn't even address if the species are in momentary stasis or a period of rapid adaptation.
I wish you well, but I just see way too many variables to have any kind of meaningful answer.
we are limited in our ability to understand
by our ability to understand
Rebel
AAmerican
.Zen
[Deist
{{{Buddha walks off laughing with joy}}}