When a publisher fails to report 6 months on a row, he is inactive, and is not counted anymore (that’s how it used to be).
In my assignment I was the only elder for a year with more than 100 publishers. A lot of people in third world countries live without papers, bills, invoices. So to report was hard for them and many just forgot. Every six months, with the visit of the CO, I spent nights visiting families to ask them if they could remember hours, magazines etc. Every six months I used to ask the CO, a fellow missionary, to talk about it in local nec. If you didnt follow it up you had easily 20-30 inactives going out in fs just because they didnt film out their report.