Why are there 12 or 13 rows?
A lunar year normally has 12 months. A leap year in the Chinese calendar adds an entire repeated month, so it has 13. This is different from a Gregorian leap year, which adds February 29.
A useful example: 2023
Lunar year 2023 includes leap month 2. It begins on March 22 and ends on April 19, a total of 29 days. Ordinary month 2 and leap month 2 are distinct date ranges.
What year should I choose?
Choose the lunar year. Its last month may end in the following Gregorian year. The table is useful for recording birthdays and checking family records; it does not identify auspicious days.