Vera is an ecologist who studies the change in the bear population of Siberia over time. The relationship between the elapsed time, $t$, in years, since Vera began studying the population, and the total number of bears, $N(t)$, is modeled by the following function: ###$N(t)=2187\cdot \left(\dfrac{2}{3}\right)\^{\Large t}$ **Complete the following sentence about the yearly rate of change of the bear population.** Every year, the bear population [[☃ dropdown 2]] by a factor of [[☃ math-keypad 1]].