Should also somehow incorporate experience level
I disagree. If people give an honest global average, i.e. what you'd see as being the absolute maximum time you'd be happy seeing from an Ao100, and I plot this against age, this will give a graph showing age/accomplishment. Ergo, if you are a 40 year old who has cubed for 12 months, but put in 4 hours practice a day, and see yourself ahead of other 40 year olds, you will probably know why. The purpose of the graph is to illustrate where you are relative to your age-peers.
I could, however, plot a different graph with global average against something like estimated hours spent cubing... but the responses (from some of the younger forumites especially) would be ridiculous. Take a look at the 'how long did it take you to be sub-20' thread - there's lots of 12 year olds who claim they did it in x weeks, and only cubed for an hour a week, and similar garbage.
I'm concerned that people will lie about their global average, which will totally skew the results. I'm intending to put something in the title thread about formatting results, something like:
Age: xx
GLOBAL AVERAGE (THIS IS NOT A LIE):
Underline and block capitals compulsory!
Happy to be a graph point. I'd be interested to see how I do compared to other people around my age.
This is my main motivation in doing this. I'm very curious to see if the results give a discernible trend.
What's your cubing progression been like?
I knew how to solve a cube when I started speedcubing, using a method I'd learnt/been taught over a period of time 10 years previously. I hadn't picked up a cube in about 5 years.
I was under a minute in a week or so, sub-50 in a month. After 2 months I was barely sup-30. It took me another 10 months to get sub-20. In the last few months I've gone from high-19 averages to low 18s. I regularly have sub-17 Ao5s, sub-18 Ao12s, but would describe myself as globally averaging 18.5-19. That's after 15 months cubing.
My progress slowed massively at around 23 seconds, where I sat for probably 6 months. This is almost certainly due to the fact I completely stopped learning new stuff, and

hours cubing a week stopped yielding the required results!
I personally found learning OLL very easy but I was dedicated. I practiced two a day every day until I know all of them. From there I drilled the ones I was having trouble with while watching movie and what not with my wife after the kids were asleep.
My wife hates it when I cube when she's watching TV. And I'm not dedicated! Trying to be - I have a blank OLL sheet waiting to have my chosen algs added to it, but I've been at around 45 OLLs for probably 3 months, and have stopped really learning anything new.
Gotta get out of the habit of not looking ahead, as well!