The results were indexed so that a value of 1 represents a perfectly connected hub with nonstop links to every other point in the network. Linkages between hub cities and other gateways in the same country (e.g., Manila±Cebu in Philippines) were not included in this analysis (Table 5). By this measure, Singapore's centrality within Southeast Asia has increased markedly since the 1970s and is substantially higher than that of its two main rivals (Table 6).