awk -F: '{
($5 in o) ? o[$5]++ : o[$5]=1
($5 in t) ? t[$5]+=$6 : t[$5]=$6
k[$2]=$5
j[$2]=$6
}
END {
for (i in o) a[i]=t[i]/o[i]
for (p in j) if((j[p]/a[k[p]])<=0.8)
printf("%s\t%s\t%d\n",p,k[p],j[p])
}
' adat