1972’s Behind the Green Door was considered part of a porno chic movement—along with Devil in Miss Jones and Deep Throat—that brought porn into the mainstream. That mainstream now amounts to several billion dollars in profit a year, or as much as $97 billion, depending on whom you believe. But of course, profit and consumption are two different things. Most porn is consumed for free. But as to how widely viewed it really is, ask yourself this—what would you think of someone who claimed they had never seen a porno movie? The answer to that question tells you how pervasive it really is. The above poster, which features Marilyn Chambers symbolically wearing a pearl necklace arranged in a not-so-symbolic X, was produced for Behind the Green Door’s Japanese run, which began today in 1976.