Freddy Sakazaki said this quote

In America, they have this thing called a story cycle. When they're at war, they start doing fantasy and war-style entertainment. When fantasy gets big, they go through a recession, and horror starts gaining popularity. When horror gets popular, mystery starts gaining popularity. Then when mystery reaches its peak, science fiction starts gaining popularity. Then things get rough again, and we go back to Fantasy. This quote was taken from an interview from The Myth of Cthulhu: Dark Navigation.