"overall decrease" is correct and usable in written English.
You can use it to refer to a general reduction in something. For example, "The company saw an overall decrease in profits over the quarter."
"It brings an overall decrease in violence".
The 2.8percentt overall decrease was the third straight month that wholesale prices have fallen.
For other categories of violent crimes, the drop matched the overall decrease for all inmates.
That was the principal cause of the overall decrease in health insurance coverage".
Recent surveys in schools also suggest an overall decrease in drug experimentation.
The overall decrease in citywide crime last year was 4.4percentt.
The president's latest budget calls for an overall decrease in federal support for elementary and secondary education.
The increasing occurrences of drought and an overall decrease in absolute rainfall promoted drier climates.
and, as you would expect, an overall decrease in the subjective sense of well-being.
Both CD4+ FOXP3− T cells and CD4+ FOXP3+ Tregs showed an overall decrease in cell numbers (Supplementary Fig. 5C).
The average effect was an overall decrease of.3percentt, within the required regulatory formula of 3percentt below inflation.
