So, what do we see? Let's just look at the middle column, where humans are allowed. The person who is by far most likely to call trump is the dealer, who ordered the up card in 30% of the hands. And second chair (the dealer's partner) called trump in 17% of the hands during the first round of choosing. Both of these stats are understandable. Ordering the up card during the first round of choosing provides additional trump to the dealer's team; the up card goes into the dealer's hand. Who wouldn't want that? Clearly, it's usually an advantage for the dealer's team to "order up"!
During the second round of choosing, when the up card has been turned face down, first chair called trump in almost 20% of the hands. I'm not sure why that happens, but I wonder if it has something to do with the "next strategy". There's a discussion thread entitled Almost Always Calling Seat 1 (Round 2) at Ohio Euchre which goes into some detail about some other possible reasons for this.
Notice that it is unusual for first and third chair to order the up card into the dealer's hand. This makes sense to me. The dealer is their opponent, and ordering up gives aid and comfort (and trump) to the enemy! You'd have to have a very strong hand of trump for this to make sense.
Also notice that it is fairly unusual for third chair or the dealer to call trump in the second round of choosing. I think the explanation for that is simple. The fact is, in most hands, someone else calls trump before the choice even gets to these players. Adding up the percents in column two, prior to "3rd chair, 3 suits", we have 5% + 17% + 5% + 30% + 18% + 11% = 86%. So in 86% of the hands, trump has been called before the choice gets to those players in round two. If you're third chair, or the dealer, and have a fairly strong hand of a suit that's different from the up card, you will likely never get the chance to call. It's often the case that you don't get a chance to call with a strong hand in Euchre - someone else will beat you to it! This is why I call Euchre a game of frustration! :)
If you enjoyed reading this page, you may want to continue reading part II, which has a more detailed analysis of the "consider" stats..