The least significant difference in this data set (lol...) is 3.09 points with a confidence value of 5%.
Average 19.5
STDEV 10.41264025
Var 108.4230769
t(0.05,13) 2.532637811
LSD 3.08890462
If your point difference is more than 3 points different from another person, then they are statistically significantly different! This doesn't mean much though since it's only based on one data set =).