Is there a list of past 4 star PvE progression rewards?

The reason I ask is that I want to anticipate what the next War Machine PvE progression reward should be.

I'm looking at a Taco Vault with both a green and a blue War Machine cover in it. My War Machine sits at 4-4-1. I don't want the blue cover if we're expecting the next progression reward to be blue, but if they've already done red and blue, then I can reasonably expect the next progression reward to be green and getting the blue won't hurt me. Did we maybe have a boss event when we should have gotten his last progression reward? Maybe green got skipped and I should expect red next?

Thank you for any information.

Please forgive me if this information is obvious and I overlooked it.