The phrase "also a substantial proportion" is correct and usable in written English.
It can be used when discussing the significance or size of a particular group or element in relation to a larger context.
Example: "In addition to the primary findings, the study revealed that there is also a substantial proportion of participants who reported experiencing similar issues."
Alternatives: "also a significant share" or "additionally a considerable amount".
Of course, there was also a substantial proportion of respondents who found flaws with the current CTA approach.
Also, a substantial proportion of the neuraminidase (25%) and hemagglutinin (21%) trunks are inferred to be outside of the seven global communities we sampled (OT).
Also, a substantial proportion of adult NGN3+ cells did not express PLZF (61%; Fig. 5D F), unlike the juvenile, where such cells were infrequent (3%; Fig. 4F).
Also, a substantial proportion of adults = 70 years of age who were free of diabetes mellitus and hypertension had stage 3 or 4 CKD or albuminuria.
Also, a substantial proportion of the sample (9.6%) was missing data on the income variable and, therefore, those subjects were not included in the analysis.
Also, a substantial proportion of the population did not consider sunbathing using sunscreen to be a risk factor for skin cancer.
It will also operate "a substantial proportion" of its European flights.
So if one party wins all or the vast majority of the constituency seats in a region, it is very unlikely to receive a list seat unless it also has a substantial proportion of list votes.
Perhaps because of the context of the data (i.e., business communication) clauses that demanded goods and services also constituted a substantial proportion of the total (25.41 %).
Their results showed that isomers from trichlorobiphenyl to heptachlorobiphenyl accounted for the majority of the commercial mixtures of PCBs, and chlorobiphenyl and dichlorobiphenyl also contributed a substantial proportion [45].
Whilst the singletons potentially contain useful lowly expressed sequences, they also contain a substantial proportion of artefacts derived from cDNA synthesis, sequencing and contamination [35].
