Ranking cities by any measure apart from population is bound to be subjective. In this ranking, published by Forbes Magazine, global cities are judged by eight criteria of which four are listed here: attractiveness to global investors (measured by the average number of foreign direct investment (FDI) transactions per year); the number of companies in the Forbes Global 2000 headquartered there; their air connectivity (the percentage of other global cities outside the city’s region that can be reached nonstop a minimum of three times per week); and their ranking in the Global Financial Centres Index. Other criteria, not listed here, include global labour force, and cultural impact, as measured by the city’s importance as global media centre.