le mapping from a Chinese year to a Western year. This is because the Chinese calendar is a luni-solar calendar. The average number of days in the calendar is close to a tropical year. Therefore, there is no secular drift between the years in the Chinese calendar and Western calendar. Hereafter, I use the notation <span class="nowrap">N<sub>y</sub></span> to denote the Chinese year whose New Year day is closest to Jan. 1 of the Western year y. For example, <span class="nowrap">N<sub>-100</sub></span> refers