'has progressively diminished' is correct and usable in written English.
You can use it to emphasize the gradual reduction of something over a period of time. For example: "The amount of rainforest land worldwide has progressively diminished in the past century."
The process of getting there will be long and dragged out, and all the while evidence will mount that whatever market power Microsoft may have been abusing when the case was first brought in May 1998 has progressively diminished, and perhaps vanished.
2, 19– 23 For instance, An. arabiensis Patton, which is typically more exophilic, zoophagic, and exophagic than its sibling species An. gambiae sensu stricto, already dominates malaria transmission in parts of western Kenya where widespread use of ITNs has progressively diminished the importance of An. gambiae s.s as the main malaria vector.
By this time, Borges suffered from total blindness, a hereditary affliction that had also attacked his father and had progressively diminished his own eyesight from the 1920s onward.
However, Woese et al. [ 48] argue that the dynamic of LGT has become progressively diminished through time as simple, primitive early cells became complex and refined.
Excessive light scattering by the suspended particles also has a progressively diminishing influence on the reaction rate.
It's weird, really – this thing has progressively grown.
However, this position has progressively changed.
He has progressively withdrawn.
Gulen's name has progressively reached a wider Western audience.
The group has progressively more secretive over time.
Advances in surgical and adjuvant therapy coupled with a better understanding of the natural history have allowed for acceptance of progressively diminished margins for distal neoplasms.
