How to find total filesize grouped by extension

find . -name '*' -type f -printf '%b.%f\0' | awk -F . -v RS='\0' '{if (NF==2) $(NF+1)=" "; s[$NF] += $1; n[$NF]++} END {for (e in s) printf "%15d %6d  %s\n", s[e]*512, n[e], e}' | sort -rn | numfmt --to=iec-i --suffix=B