Reference to stats on conversion rates for SaaS/Ecommerce?

Does anyone have references to high quality studies on conversion rates for SaaS / Ecommerce sites?

Ideally large sample size studies that have been completed in the last few years.

I'm specifically trying to understand the average % of ecommerce shop visitors who end up buying something, as well as SaaS landing page visitors that end up converting to paid users.

Would really appreciate any pointers!