In all those countries, average salary for JP Morgan employees is significantly higher (especially if you include expats). Also I think you are significantly off with Nigeria avg salary - no way it's so high in such a poor country.
Nigeria is tricky - I've seen estimates ranging from $130-$750. World Bank classifies it as a "lower middle income" country at this point, which would suggest they at least think the median is <$4k or so per year, I think.
Venezuela avg salary 230$ per month
Vietnam avg salary 277$ per month
Lebanon avg salary 190$ per month
Nigeria avg salary 730$ per month
Pakistan avg salary 293$ per month