plot    fleas  ragwort
   1     12.2   18.200
   2     14.6   17.500
   3     15.8    7.220
   4     25.3   30.600
   5     38.6    6.660
   6     76.4    6.140
   7    163.0    5.210
   8    182.0    0.502
   9    415.0    0.611
  10    446.0    0.630
  11    628.0    0.427
  12    377.0    0.011
  13    770.0    0.012
  14   1446.0    0.006
  15   1012.0    0.002