plot.R

# Create map
( ggplot()
+ geom_polygon( data    = data
              , mapping = aes( x     = long
                             , y     = lat
                             , group = group
                             , fill  = players
                             )
              , color   = "white"
              )
+ labs( fill = "Players born" )
+ coord_map() 
+ theme( panel.grid.minor = element_blank()
       , panel.grid.major = element_blank()
       , panel.background = element_blank()
       , panel.border     = element_blank()
       , axis.ticks       = element_blank()
       , axis.text.x      = element_blank()
       , axis.text.y      = element_blank()
       , axis.title       = element_blank() 
       )
)