ZDNET UK: A Year Ago: Red Hat attempts Linux headcount

“First published: Thu, 12 Mar 1998 18:12:29 GMT Red Hat Software
has released its latest estimate of the installed Linux user base,
putting it at between 5 and10 million people worldwide.”

“With no one vendor having overall control of distributing
Linux, precise figures are hard to come by. Red Hat’s figures are
based on several sources including the number of Linux Journal
subscribers and surveys published by such magazines as Dr. Dobbs
and UNIX Review.”