DesNews reported 21 Utah football players are RMs in 2014. I could find no specific information on how many on the team are LDS, but by a rough count it is about 28 (basically picking guys I knew were LDS and also guys from Utah... that number is likely lower, but definitely not higher as being from Utah doesn't automatically make you higher). So about 75% of the LDS players are RMs.

By the same article, 61 players on BYUs squad are RMs. I don't know how many non-LDS people are on your squad, but maybe... 10 (Bronco said in another article that 90% of his team was LDS, I'm giving you +1.5 to help the percentages)? Maybe you can provide better numbers. But it looks like ~81% are RMs. Given the smaller amount of LDS kids on Utah's team, if they added a single RM (and they did for 2015 with Chase Hansen at least) that puts them at about 79%.

I wasn't expecting to see Utah have nearly the same percentages of LDS kids on missions than BYU, but it looks like what you are saying doesn't hold much water. Of course, if there are hard counts, given the small numbers those percentages can be swayed pretty dramatically with a +2 or -2 here or there.

I have no idea how 2014 compares to other years as far as percentage of LDS kids, but I would guess it has been around 35% for quite a long time.