How did my ally achieve a higher economic score?

I am blue, and achieved an economy score of 5457. My ally, grey, achieved a notably higher economy score of 6698.

However, when taking a closer look at economy stats...

As the screenshot depicts, I obtained more resources than grey in every category. Not the highest in the game, but definitely more than what grey collected.

How can my ally have more than 20% higher economy score even though I obtained more of every resource during the game? Are there additional factors that economy score takes into consideration other than what the achievements screen displays?

(Military, Technology, and Society scores are included in case they play a factor into it.)