Each subscriber has one or members associated with his/her contract. An employee/retiree/COBRA only siubscriber has 1 member associated with his/her contract. Employees/retirees/COBRA beneficiaries with covered dependents have 2 or more members associated with his/her contract.
Hence a higher ratio (never less than unity) denotes more covered dependents. Typical ratios for subscribers with 1 dependent range from 1.8 (minor child) to 2.2 (spouse of child-bearing age) while typical ratios for subscribers with multiple covered dependents can range as high as 4.0 (e.g., employee, coverred spouse and 4 minor children).
I hope this sounds elementary.