Today I learned something that sounded like a joke - the only team in the world that took part in all FIFA World Cups is Brazil. I checked the data and it seemed that it's true. On the map below you can see the qualifying percentage by country. Note that due to the World War II Germany was out for a while, but still it has 100% success rate.
The number of appearances (below) is led by Brazil with total number of 21. Germany has 19 and third is Italy with 18.