The phrase 'accumulated over years' is correct and usable in written English.
You can use it to describe how something has grown, built up, or become larger over a period of time. For example, "Our family-owned business has accumulated an impressive fortune over the years."
"This isn't something he accumulated over years, but bought in a four- or five-week period.
Other leaders, like Liberian President Ellen Johnson Sirleaf, expressed frustration with fallout from the global economic crisis that she said has "eroded benefits accumulated over years of reform".
The goal was to clear underbrush that had accumulated over years in which federal policy has emphasized suppressing fires, rather than allowing them to run their course.
She is moving house and won't have shelf space for a library accumulated over years of preparing meals for family and friends.
Most of the trucks are from Mr. Guerrera's personal collection, which he accumulated over years of drifting through junkyards, looking for ghosts from trucking's Golden Age, which in his view was the 1950's.
Meanwhile, economic, social, political and environmental problems have accumulated over years of unbalanced, breakneck growth in a state-dominated economy – and threaten to become still more evident as the pace of growth ebbs.
Bennett suspects that the effect accumulates over years, meaning there is no quick fix.
Scientists from the Baylor College of Medicine, Texas Children's Hospital and Johns Hopkins University School of Medicine targeted ways of reducing the amount of toxic proteins that accumulate over years in the brains of those who subsequently develop Alzheimer's.
The costs of long term remediation projects accumulate over years and effectiveness is only observable after a long time [ 33].
Results were accumulated over 10 years, the time taken for 100 doctors to complete at least five years of monitoring.
Criticisms, too, have accumulated over the years.
