After the last ice age began, the number of plant species in South America changed rapidly. The relationship between the elapsed time, t, in years, since the ice age began, and the total number of plant species, P (t), is modeled by the following function: P(t)=30,000,000⋅(89)t Complete the following sentence about the yearly rate of change of the number of plant species. Every year, the number of plant species grows/shrinks by a factor of __