The difference between the amount of products when conducted from 350-200 or at 200?

[yzdm]

Here is a detialed description.

I ran a reaction under temperatures from 350 to 200 and at the temperature of 300, 250, 200, respectively.

For example, i compared the amount of products at 300 (the reaction conducted from 350-200), however, these amounts are different from the value when i ran the same reaction at the temperature at 300.

Why does this happen?