Have added a second dot for Cotonou, but have still kept it as the same answer as Porto-Novo since they're both considered Capitals. Have also added in Timbuktu, won't add the islands as they're too small to be shown distinctly on the map. They're also primarily in Cape Verde, which isn't so good since that's entirely islands! Thanks for the suggestions though :)
The other cities are the largest non-capitals roughly. Just happens that Nigeria has like the same population as the other 15 countries! This is also not an extensive quiz, but rather a summary of various Physical and Human geographics.