There are many solutions to plot maps at country level, but in my case I want to print statistics at continent level.
The only thing that comes into my mind is to us
library(sp) #Load your libraries
library(maptools)
#Download the continents shapefile
download.file("http://baruch.cuny.edu/geoportal/data/esri/world/continent.zip",
"cont.zip")
#Unzip it
unzip("cont.zip")
#Load it
cont <- readShapeSpatial("continent.shp")
#Plot it
plot(cont,
col=c("white","black","grey50","red","blue","orange","green","yellow"))
#Or any other combination of 8 colors