Because of high mortality and low reproductive success, some fish species experience exponential decline over many years. Atlantic Salmon in Lake Ontario, for example, declined by 80% in the 20-year period leading up to 1896. If xt denotes the number of Atlantic Salmon per square kilometer in Lake Ontario in year t, where year 0 is 1876, then we can model the decline in the number of fish per square kilometer with a DTDS of the form xt+1=rxt. Given the data above, calculate the value of r. Give your answer with an accuracy of three decimal places.