"Year-on-year" means the ratio of the same period, generally referring to the comparison between the cumulative indicators of a certain month of this year and the cumulative indicators of the same month of the previous year. As the name suggests, "year-on-year decline" refers to the ratio between the cumulative indicators of this year and the cumulative indicators of the same month of the previous year.

Calculation formula: ( ( b - a ) /b ) * 100