fair share

First attested in the mid-1600s.

fair share (uncountable)

An equitable or reasonable portion, especially in regards to contributions towards a particular duty, or the dividends thereof.
As the company had no dedicated janitor, all employees were expected to do their fair share of cleaning up after lunch.
(idiomatic) A significant amount, often implied to be excessive or inordinate; a great deal of something.
He endured a fair share of criticism during his lifetime, but his works are now universally considered to be masterpieces.
- 2023 November 11, Matthew Howarth, “Arsenal 3-1 Burnley”, in BBC Sport:
  Arsenal have had more than their fair share of injury troubles in recent weeks, but they were given a welcome boost before kick-off as Saka and Takehiro Tomiyasu, who both suffered knocks in Wednesday's 2-0 win over Sevilla, were passed fit to start.

Prior to the 1950s, the indefinite "a fair share" was in equal usage as possessive forms, such as "their fair share". However, this has steadily declined, and according to Google Ngram data, possessive forms are now roughly four times as popular as the indefinite. The definite form, "the fair share", has never been common, and has fallen from a peak of 3.2% of total uses in 1989 to less than 0.7% in 2019.
To avoid ambiguity between the senses of "an equitable portion" and "an excessive amount", it is common to use the idiom "more than one's fair share".
He's had more than his fair share of time in the courtroom.

equitable portion

significant or excessive amount

English