We don’t currently have any internal reporting for that metric.
The best way to do this currently would be to listen to the user.login.success event.
This event will contain what IdP was used and more info. You can then push that to whatever analytics storage layer (database, s3, etc) you'd like.
More here: https://fusionauth.io/docs/v1/tech/events-webhooks/events#user-login-success