The phrase "a massive decline in" is correct and usable in written English.
It can be used to describe a significant reduction or drop in a particular area, such as statistics, performance, or resources.
Example: "The report indicated a massive decline in sales over the last quarter, prompting the company to reevaluate its marketing strategy."
Alternatives: "a significant drop in" or "a substantial decrease in".
Some 76 per cent of North Sea operators are less confident about their North Sea activities than they were a year ago – a massive decline in optimism since the previous Chamber of Commerce survey six months ago, when the figure was 46 per cent, and the lowest level since the survey began in 2004.
There was a massive decline in the supply of labour.
Some researchers predict a massive decline in the viability of food crops critical for human survival.
But there's been a massive decline in the grant that we've been given.
We've had a massive decline in gun violence in the United States.
In Europe, such awfulness would have been punished with relegation and a massive decline in TV and sponsorship revenue.
Regretfully, the Galapagos Islands are now inhabited by the same three elements that triggered a massive decline of endemic birds in Hawaii: the Avipoxvirus; competent vectors in Culex quinquefasciatus and perhaps other mosquitoes; and the recently detected Plasmodium blood parasite [39].
On the whole, however, the early decades of the Industrial Revolution saw a massive decline of popular leisure traditions; even in the countryside, festivals were diluted by importing paid entertainers from the cities.
This category has seen the biggest drop of the year at 12percentt down from 48percentt in 2016 – a massive decline.
The massive decline in energy use relative to economic output was not a function of price increases.
Conservative housing spokesman Mark Isherwood said the "massive decline" in house building under Labour since 1999 had caused a housing supply crisis.
