n = 600, weights in [1,1000], one random graph per row

       |E|       |E|/V      Floyd (ms)    Johnson (ms)    winner
      1200         2.0            21.6            12.9   Johnson
      3000         5.0            86.1            38.2   Johnson
      6000        10.0            99.3            56.7   Johnson
     12000        20.0           103.5            78.3   Johnson
     24000        40.0           112.5           103.1   Johnson
     48000        80.0           113.6           133.2     Floyd
     96000       160.0           115.7           171.7     Floyd
    180000       300.0           116.4           217.6     Floyd
    360000       600.0           118.6           301.5     Floyd
