The key to Switzerland being well armed is the Fact that Every Male is expected to serve in the military...and they are allowed to keep their Military Issued rifle when they are through with their military service, which most take advantage of.
That article says that there are enough firearms out there to arm roughly 9 out of 10 Americans....not stating that 9 out of 10 Americans are armed.
Switzerland probably has the highest percentage of their citizens armed.
Yemen is the Scary one on that list coming in at number 2...
....that's some scary chit there