"steeply increased" is a perfectly correct and usable expression in written English.
You can use this expression to describe a situation in which something has grown in a rapid or dramatic manner. For example, "The demand for the product has steeply increased in recent months."
After those hurricanes, insurers either left the Florida market or steeply increased their polices' rates.
In the case of OPC-silica fume (SF) system, yield stress and plastic viscosity steeply increased with increasing SF.
Although NIm was almost independent of the vapour generation rate and impeller designs, NHe rather steeply increased with an increase in the vapour generation rate.
Toward this end, the number of proton radiotherapy facilities has steeply increased over the last 10 15 years to currently around 70 operational centers worldwide.
The value of d/d0 was about 1.2 for Tprep=20 °C, but steeply increased by approaching the phase separation temperature ≈32.0 °C.
On the other hand, Ti film deposited by conventional magnetron sputtering possesses a steeply increased RMS surface roughness of 6 nm.
Another 2.5% have a steeply increasing BMI.
Finally, I steeply increase the spices.
A steeply increasing number of research works present promising results and applications in biomedicine, diagnostics and analytics as well as nanoelectronics.
But the team takes advantage of the tiny magnetic moment of the antihydrogen atom to trap it using a steeply increasing field — a so-called magnetic mirror — that reflects them backward toward the center.
"These challenges require urgent action in the areas of the financial sector, state-owned enterprises and microeconomic reforms in order to prevent a situation in which severe imbalances would steeply increase towards unsustainable levels," it said.
