How Shannon entropy calculated per codon?

Thanks
Can you download ncov_global.json in https://github.com/Developercovid/auspise.git and see it in https://auspice.us/.
for example for Codon 220 in protein N number of mutation(Events) is 1 and Entropy of this codon is 0.690.but When I calculated Entropy with formula that you send for this codon the result is 0.055.why?