According to my site logs, which may not be the last word in accuracy, Google+ didn't refer a single visitor yesterday.
There have been a total of eight Google+ referrals in the past seven days. According to this site's lifetime statistics a total of around 1000 referrals from 250,000 visits.
I get 16 Twitter referrals for every Google+ one. Reddit and Stumbleupon do better than Google+. Facebook does slightly worse, but I barely spend any time there.
To be fair, this site was hosted elsewhere during Google+ heyday.
The glory years were 2011 when Google's social networking site first got moving and 2012 when, momentarily, Google+ looked like it may challenge Facebook. I remember days when 100 or so visitors would roll in through these doors from a link on Google+.
Yet, it's clear the numbers have fallen from a steady stream to a trickle. It's not for want of trying. There's a better class of comment on Google+ and it attracts a distinctly different audience from other social networking sites.
At one point I looked at integrating my comments with Google+, but that was never going to be simple.