Also, it's low because this is applicants per place. Look at applicants per offer, and you'll get a very different statistic for many universities. Cambridge gives out around 1.2 offers for every person who matriculates. Bristol, in contrast, gives out 5-6. So while Bristol may have 20 applicants per place, over 25% of applicants get offers, it's just many of them refuse their offer or don't meet their grades.