The phrase "and the same proportion" is correct and usable in written English.
It can be used when discussing ratios or comparisons that maintain a consistent relationship between quantities.
Example: "If we increase the amount of flour, we should also increase the sugar and the same proportion to maintain the recipe's balance."
Alternatives: "in the same ratio" or "in equal measure".
Two thirds of patients felt their physical health had improved, and the same proportion reported better mental health.
Two-thirds exposed themselves on a webcam or in a photo, and the same proportion actually set up a rendezvous and travelled to meet the 'child'child
Two-thirds of them are deemed poor, 40% or so are unemployed, and the same proportion of adults has HIV/AIDS.
Members of the Asia-Europe Meeting group, or ASEM, account for nearly 60 percent of the global population — and the same proportion of global trade.
Demographically the state mirrors the nation, having the same division between urban and rural voters, and the same proportion of blacks as the country at large.
Even in America around a third students enrolled in college never complete their degrees, and the same proportion of all first years undergraduates have taken at least one remedial course in reading and/or mathematics.
The study, which took samples from 390 phones in 12 cities, raises serious public health concerns as it found that 16% of hands and the same proportion of phones were contaminated with E coli.
The English theatre scene is "shrivelling", according to research, with two-thirds of venues cancelling productions, half producing fewer new plays and commissioning fewer writers, and the same proportion obliged to insist playwrights focus on smaller cast sizes.
In the Republican primary, Mr. McCain got 38percentt of voters unaffiliated with either party, and the same proportion of registered Republicans, according to exit polls conducted by Edison/Mitofsky for the television networks and The Associated Press.
According to the US Education Trust, only 20% of students at for-profit colleges complete a four-year course and the same proportion of those who do finish, default on their loans within three years".
The DWP insists three-quarters of those who go on the scheme say it improved their personal confidence, and the same proportion felt "positive" at the end of the placement.
