Average Retention Rate calculates the percentage of customers with more than 1 order out of the total number of customers.
An average retention rate of 20% means that only 20% of all customers came back and placed the 2nd order while 80% stopped purchasing after the first one.
It may be worth understand what stopped them from placing other orders through research instruments like online surveys.
For most industries, average eight-week retention is below 20 percent. For products in the media or finance industry, an eight-week retention rate over 25 percent is considered elite. For the SaaS and e-commerce industries, over 35 percent retention is considered elite.