Zero.
People get those awards for 99% not 97 %
Not at all necessary.
If you pay close attention to the lists, the value of distinction is variable i.e. it is centered on cities or the country itself. Hence, if per se, student from your city didn't score more than 96% on the UMS, then you will be distinction holder for your city. Same can happen for your country, but the chances for that are almost null. A worldwide distinction holder is the one who would have achieved 100% UMS.