Are ipads used horizontally or vertically?

I found this old question:

iPhone/iPad: Do people use landscape mode?

But considering the now venerable age of the ipad I think conventions may be more established now.

So, my question is, what percentage of users use ipads horizontally/vertically?

Are there any statistics about this? (Is it possible for websites to collect that data?)

My instinct suggests that horizontal may have won out- due to most ipad stands/cases being best designed to support a horizontal orientation. Though considering someone holding ipad, portrait strikes me as perhaps the most ergonomic. hmm.