"But I think we can go further and learn from what's happened over the last few years."

I know what's happened over the course of the past eight years.

What has happened over these three and a half years or more?

Exactly what happened over the next half hour is not clear.

It had happened several times before over the last couple of months.

Despite everything that had happened to him over the last few years, he'd never quite let go of the hope.

She closed her eyes and let herself think back on what had happened over the past two months.

He never used to be that way, and did not know what had happened to him over the years.

That is exactly what has happened over the last year.

That has not happened over a similar period since 1953.