271
One third of the population of Switzerland lives within 5 kilometers of the main train line crossing the country
(reddthat.com)
Source (yes sorry it's LinkedIn, if you any another one, I'll update): https://www.linkedin.com/posts/prof-stefan-michel_notsweden-train-activity-7210174690827370496-8iJz?utm_source=share&utm_medium=member_ios
I believe something like 80% of the population of Brazil live within 50 km of the coast.