Answer
$1.25$ teams per year.
Work Step by Step
The average rate of change of $f$ over the interval $[a, b]$ is given by:
Average rate of change of $f\displaystyle \ \ =\frac{f(b)-f(a)}{b-a}$
The units of the average rate of change of $f$ are units of $f(x)$ per unit of $x$.
Average rate of change of $f\ \ $ over $[4,8]$ is
$\displaystyle \frac{f(8)-f(4)}{8-4}=\frac{1013-1008}{4}=\frac{5}{4}=1.25$ teams per year.
