The current I in an inductance coil varies with time according to...

The voltage across an inductor is

$V = - L\dfrac{di}{dt}$

So the voltage across the inductor will always be opposite to the rate of change of current.

When $\dfrac{di}{dt} > 0$ then $V < 0$ and vice versa

Also, the magnitude of $V$ is proportional to the magnitude of $\dfrac{di}{dt}$.

When $\dfrac{di}{dt}$decreases, $V$ also decreases