What does "99" mean?

You know, "March 9th was very cold. Is the heat in the middle? 1939 was followed by 1949, 1949 was followed by 1959 ... until 1999. . This is called "counting nine". Count the days from winter to Sunday, nineteen, twenty-nine and thirty-nine. Nine days is nine days. Counting nine times is "counting nine".

"Ninth Five-Year Plan" means the degree of weather temperature change. 19, 29 years old, unable to reach out; Walking on the ice on March 9 and April 9; Look at willows by the river in May and June, talk about rivers in July and September, talk about geese in August and September, and talk about scalpers in September and August. It is also said that 99 poplars landed and 19 apricot blossoms bloomed. 1999, farmers began to work in the fields. At that time, I cooked at home and ate in the fields.

These are the numbers written on the yellow calendar, such as 49 and 59, and then 69, 79, 89 and 99.