Off topic: Numbers of Internet engineers/operators

This is probably off-topic for the list, so I apologize.

I'm trying to find some numbers (surveys, etc) that show the
numbers of network engineers and operators (ie operations
people, network engineers, network architects, possibly
systems engineers, sysadmins, etc--for both Internet and/or
intranet networks) that are working on the Internet today
and maybe projections for the future. Numbers on personnel
shortages would be good, too.

Thanks for any references you can give me.