In the sample provided, which I assume is a photograph of the printed sheet, the numbers for the four sites would not present a green component.
L value: the tone level with white at 0 and black at 100
a value: a measure of Magenta/Green with a positive number indicating Magenta
b value: a measure of Yellow/Blue with a positive number indicating Yellow
Since green (minus value in the a channel) does not appear in any of the samples, you may consider this as probably an optical effect, an illusion, called simultaneous contrast. One detailed explanation of the phenomenon may be found in a book by Dan Margulis: “Photoshop Lab Color” second edition. You can also google the term.