eComm pals: What % of your CRM database are people who signed up for email but never placed an order?

I’m doing an analysis of who our database consists of, which made me realize that 88% of our database NEVER purchased our bestselling product, which then made me realize that 2/3 of our database are people who never actually bought anything from our brand .com. I’m wondering what’s the benchmark for EComm sites in terms of non-customers in the db.

Thanks!