This combination creates the 60-year cycle due to the fewest years (least common multiple) it would take to get from "Yang Wood Rat" to its next iteration, which always starts with "Yang Wood Rat" and ends with "Yin Water Pig". Since the zodiac animal cycle of 12 is divisible by two, every zodiac sign can occur only as either yin or yang: the Dragon is always yang, the Snake is always yin, etc. The current cycle began in 1984 (as shown in "Table of the sixty-year calendar" below).