The phrase "started decreasing" is correct and usable in written English.
You can use this phrase to describe any kind of decrease, such as a number or value that has begun to go down over time. For example, "After peaking in May, sales started decreasing in June."
The equatorial reflection of α (at 2θ=20.4°) started decreasing at ϵ∼15%.
Optical staining techniques showed that the average silane thickness started decreasing after 12 years of service.
Serum iron, cholesterol and total protein initially increased, and then started decreasing with incremental levels of A. tortilis.
Expression of γ-kafirin started decreasing after 21 DAP and a very low expression was detected at 28 DAP.
The computed scattering coefficients showed increasing behavior from transplanting to reproductive stage and started decreasing at ripening stage.
In the abiotic environment only a slight molecular weight decrease was seen and the polydispersity started decreasing towards 2.0.
"Then shelf space started decreasing and decreasing for mass market, and it has especially declined in the last several years".
After the Nuclear Test Ban Treaty was ratified by the USA and the Soviet Union in 1963, atmospheric tritium levels started decreasing as a result of its radioactive decay and atmospheric removal by precipitation.
The steepness of the C V response of the as-deposited structures first increased with the increase in deposition rate until 60 nm/min and then started decreasing with the further increase in the deposition rate.
While imposex in the former started decreasing in 2006 and by 2009 the EcoQO had been met in the area, VDSI in the latter was not significantly reduced until 2011 and values contradict such an achievement.
The resolution of N-acetyl-protected substrate -2 showed excellent E (>200) after 30 min, but as the reaction progressed, E started decreasing after 2 days, because of N→O and O→N acyl migrations.
