I don't think it is zero but where we have sites like wikipedia, they should be much lesser than the exorbitant prices they charge for subscriptions. You can't

I don't think it is zero but where we have sites like wikipedia, they should be much lesser than the exorbitant prices they charge for subscriptions. You can't read what you need but what the publishers think you should subscribe which is worse than proprietary software because this is Science - This has become the industry standard for journal publishers.