1. The article lists the top five countries with the best and worst costs for mobile data, based on the percentage of mobile data cost to salary and the phone plan cost in USD. 2. Singapore ranks first with the lowest mobile data cost as a percentage of salary at 0.35%, followed by Luxembourg, Israel, Iceland, and the United Kingdom. 3. On the other end, Guinea has the highest mobile data cost as a percentage of salary at 56.29%, with Zambia, Ivory Coast, Syria, and Papua New Guinea also having high costs.