How many years does social security pay a grade?

Dear, I checked the number of years (commonly known as "length of service") for you to pay the social insurance fund. The longer you pay the social insurance fund, the higher the pension amount. Some provinces, autonomous regions and municipalities directly under the Central Government divide the length of service into six grades: 15, 20 years, 25 years, 30 years, 35 years and more than 35 years. The higher the grade, the higher the pension amount. In some places, regardless of grades, one year's service is counted as one year, and the longest service is 44 years (according to 16 years old, retirement at 60 years old).