"swelling proportion" is a correct and usable phrase in written English.
You can use it when referring to an increase or growth in size or number relative to something else. Example: The city's population has been rapidly growing over the past decade, resulting in a swelling proportion of young families in the community.
One of the consequences, he writes, is that "for a swelling proportion of citizens, the names of Luting, Dien Bien Phu and My Lai will always be much more evocative than those of Kokoda, Tobruk and Gallipoli".
Modern society is nowadays invariably faced with the daunting challenge of having to care for its consistently swelling proportion of the frail elderly.
Consistently swelling proportion of the frail elderly within a modern society challenges the overstrained public health sector to provide both adequate medical care and comprehensive assistance in their multiple functional deficits of daily living.
The swelling ratio versus time curves obtained in DMSO-rich solvents were shown to be of anomalous swelling type: the swelling ratio first increased in proportion to time for a while and then catastrophically expanded on approaching the equilibrium ratio.
Swelling ratio percentage.
("I am in a very bad mood," he wrote to a friend. "Making no headway. The project I have chosen is incredibly difficult. There is no end to the preliminary research, the outline is swelling out of all proportion and I feel my strength ebbing away").
The swelling factor increased in proportion to the SIA at all pressures.
The old ones are full of longing & half-spoken promises, starting with a tentative call & swelling to huge melancholy proportions.
The steady heave of the two mixtures is highly indicative of the gradual onset of osmotic swelling [15], indicating a significant proportion of sodium-montmorillonite.
Mr. Gates said he wanted to flatten a bureaucracy that had experienced significant "brass creep," swelling to "cumbersome and top-heavy proportions".
