The phrase 'greatest decrease' is correct and usable in written English
You can use it when you want to refer to the maximum decrease that has occurred in something. For example, "The number of daily visitors to the museum dropped by 30%, which was the greatest decrease in the past year."
According to the Pew report, "Between 1997 and 2007, New York experienced both the greatest decrease in violent crime and, simultaneously, the greatest decrease in prison population and incarceration rate of any state in the country".
According to the World Bank, in the three decades between 1981 and 2010, we witnessed the single greatest decrease in material human deprivation in history.
"Consistently," Dr. Laden said, "in the cities where there was the most cleanup, there was also the greatest decrease in risk of death".
The greatest decrease in consumer prices is apparent in Ireland and Great Britain, where clothing prices have fallen by about 50 percent.
However, writing in the Guardian, Fox says the argument should be made more strongly that globalisation has resulted in "the single greatest decrease in material human deprivation in history".
Also, those with low baseline levels of slow-wave sleep had the lowest levels after having their sleep patterns disrupted; they also experienced the greatest decrease in insulin sensitivity.
The greatest decrease in MCwb 20-322% depending on treatment) occurred under summer storage (Table 3).
While the ESP exhibited the greatest decrease when the soil was treated with LRC and CSB13.
The greatest decrease was observed for uncrosslinked PTMSP, while nanocomposite PTMSP films showed the least decrease.
The greatest decrease in average diameters of myelin fibres and theirs axons was noted at F50 and WA30.
Similarly, the greatest decrease in oil viscosity was found in the culture medium supplemented with yeast extract.
