However, the breakdown is heterogeneous across the different countries in the region (Map 3.7). In 2010, the NAP/AP was above 1 in 10 countries, including all countries of the Gulf of Guinea: Benin, Cape Verde, Cote d'Ivoire, Gambia, Ghana, Guinea Bissau, Liberia, Nigeria, Senegal and Togo. This relationship implies that the probability of belonging to the agricultural sector declines with the size of the city. The parameter p is the elasticity of the NAP/AP ratio of an urban centre of size V compared to the variable U/R. This formula expresses the second assumption of the model: the more developed an economy, the more urbanisation, represented by the U/R ratio, is advanced, and the more the agricultural fraction of the population of a town of a given population is low.