The phrase "relatively large proportion" is correct and can be used in written English.
Example: "In comparison to other countries, a relatively large proportion of the population in Japan is over the age of 65."
The relatively large proportion (26%) of minority probands largely reflects the oversampling of these families at the San Francisco site.
Both companies want to hold on to a relatively large proportion of the ad revenue they generate.
A relatively large proportion of MLLs (42%) were diagnosed in women older than 55 years.
They found "to their surprise" that "a relatively large proportion of genetically modified DNA survived the passage through the small bowel".
Occupied habitat by sage-grouse was more variable but also had a relatively large proportion of treeless areas (−x = 71, SE = 5%).
Still, screening for the right clone can be tedious because the high incidence of illegitimate assembly results in a relatively large proportion of missing or shuffled DNA elements.
The influence of intersection features on safety has been examined extensively because intersections experience a relatively large proportion of motor vehicle conflicts and crashes.
The scientists said that high prevalence of the gene variant could explain why a relatively large proportion of people have difficulty with remembering faces.
There was substantial variation among clinical researchers in their acceptability judgments, with a relatively large proportion of clinical trial investigators willing to accept provisions that give industry sponsors considerable control over the dissemination of research results.
A relatively large proportion of individuals with submicroscopic infections had negative samples in preceding and subsequent surveys (this occurred in at least 30% of submicroscopic episodes in five of the cohorts).
Although the nuclear household still occupied the largest proportion, the single-person household was becoming more numerous, and the extended-family household still maintained a relatively large proportion.
