=+5.67 ● The article “The Epiphytic Lichen Hypogymnia physodes as a Bioindicator of Atmospheric Nitrogen and Sulphur Deposition in Norway” (Environmental Monitoring and Assessment [1993]: 27–47) gives the following data

(read from a graph in the paper) on x 5 NO3 wet deposition

(in grams per cubic meter) and y 5 lichen (% dry weight):

x 0.05 0.10 0.11 0.12 0.31 y 0.48 0.55 0.48 0.50 0.58 x 0.37 0.42 0.58 0.68 0.68 y 0.52 1.02 0.86 0.86 1.00 x 0.73 0.85 0.92 y 0.88 1.04 1.70