The following data comes from a study on the effects of sunlight on pea plants, where x = distance (in centimeters) from an ultraviolet light source and y = sunburn index.

x18 21 25 26 30 32 36 40 40 50 51 54 61 62 62

y4.0 3.7 3.0 2.9 2.6 2.5 2.2 2.0 2.1 1.5 1.5 1.5 1.3 1.2 1.1

The Correlation Coefficient for this data is r =