For a year, number of Linkedin users is going exponential vs time. When I look at number of connections vs network ratio (for myself), it can be seen that people are more and more connected with each other.

I am not inviting any more people as I reached the number of people I am allowed to invite. The growth seen in the green curve (numbers of 1st level connections) is purely passive.

I have received 12 invitations per day for the last year. I am not advertizing my email anymore in my profile as it is now "strictly" forbidden, I mainly receive invitaions from LIONS and toplinked users. By the way, I did not see any diminution in the number of received invitations when removing my email from my profile.