dramatic, large, sharp, significant
There has been a sharp decrease in pollution since the law was introduced.

slight, small | gradual, progressive, steady | corresponding
Fewer houses are available, but there is no corresponding decrease in demand.

show
This year''s figures show a decrease of 30% on last year.

report
Half the companies in the survey reported a decrease in sales.

cause, lead to, result in

on the ~
Marriage is still on the decrease.

~ from … to …
a decrease from 62% to just under half

~ in
The new treatment led to a huge decrease in the number of deaths.

~ of
a decrease of 20%

~ to

considerably, dramatically, drastically, markedly, significantly | slightly
Spending has decreased slightly this year.

rapidly | steadily | gradually

by
Crime has decreased by 20 per cent.

from, to
Average family size has decreased from five to three children.

with
The number of quarrels among children decreases with age.

decrease in number/size/value
The heart gradually decreases in size.