the better part of, It is past time to reform

What kind of government leaves a mountain of explosive chemicals lying around unsafely for the better part of a decade?

ECONOMIST.COM
It is past time to reform Lebanon's corrupt and broken state
A succession of crises

the better part of

 

most of:

We waited there for the better part of an hour.

Note:

• Used to emphasize that most of a period of time was spent doing something.