During the 16th century almanacs and calendars were the most frequently printed books besides editions of the Bible.
"Cheap almanacs were the most important of these texts, distributed in vast numbers at a cost of one or two pence from the sixteenth century. Six hundred titles were published by 1600. Hundreds of thousands were sold in the sixteenth century and millions in the seventeenth. Almanacs made by the parliamentarian astrologer William Lilly sold up to 30,000 copies were year during the civil war, earning him up to £48 per year from sales. By the Restoration about 400,000 almanacs were sold annually. The printers dramatically helped make English almanacs into such popular works. When the seventeenth century antiquarian Robert Plot tried to explain the traditional use of clog almanacs, portable or domestic tally rods marked with the lunar cycle and feast days, he applied to the new familiarity of print, 'we have have them now since the invention of printing; some Almanacks being fitted to hang up in our houses and others for privat use, which we carry about us'. Apart from the Bible they were surely the most widely distributed forms of print and were certainly not limited to vulgar readers, offering linkages between elite and plebeian cultures. They appeared as broadsides, or most commonly in cheap octavo format with three sheets folded into twenty-four leaves, printed in black letter until amost the end of the sixteenth century. An innovation of 1571 due to the very prolific early Elizabethan almanac maker Thomas Hill, author of a host of cheap works on physiognomy, dream interpretation, husbandry and distillation, was the inclusion of interleaved blank pages so that long-term almanacs could be used as diaries" (Simon Shaffer, "Science" IN Raymond, Joad, editor, The Oxford History of Popular Print. Volume 1. Cheap Print in Britain and Ireland to 1660  402).