Compared with the revenues earned by other mass media industries, the steady growth of book publishing has been relatively modest. From the mid-1980s to 2012, total revenues went from $9 billion to about $27.1 billion. Within the industry, the concept of who or what constitutes a publisher varies widely. A publisher may be a large company that is a subsidiary of a global media conglomerate and occupies an entire office building, or a one-person home office operation using a laptop computer.