Handle sparse results

c-historico/handler.cr

@@ -101,10 +101,13 @@ class Handler
           x = (1922..2015).to_a
           y = x.map { |_| 0 }
         else # We got results
-          displayed = true
+          values = Hash(Int32, Int32).new(default_value: 0)
           results.map { |r|
-            x << r[0].as_i
-            y << r[1].as_i
+            values[r[0].as_i] = r[1].as_i
+          }
+          (1922..2015).map { |year|
+            x << year
+            y << values[year]  # Defaults to 0, so we have the whole set
           }
         end
         plot(x, y, title: nombre.titleize, style: :lines, linewidth: 3)