With Omniauth, How to record all requests for authentication?

With Omniauth, How to record all requests for authentication?

with omniauth in my app, to have a user use Google oAuth2 to authenticate
I redirect the user to:
/users/auth/google_oauth2
If the users approves the request, then the
AuthenticationsController#create is called.
With AuthenticationsController#create - I can add event tracking to record
the # of users who approve google auth. What I don't have is the number
that I sent to approve meaning I don't have a conversion rate.
How can I track the # of people who hit the URL around making requests to
connect.