I wonder, check your paraphrase for graduate again, since you use "undergraduate" and it have different meaning with graduate. Here I give you the definitions, based on oxford dictionary.
Graduate is a person who has successfully completed a course of study or training, especially a person who has been awarded an undergraduate or first academic degree.
Undergraduate is a university student who has not yet taken a first degree.
Almost thirty thousand of graduate students opted for further study and 2725 postgraduate student went for higher studies
It is better to make a clear comparison between the data.
There are more of graduate students who opted for further study by virtually thirty thousand, while there are just 2,725 of postgraduate who went there.
large proportion of undergraduate students were unemployed after the completion of their degree,that is about 16000
Using large proportion
are less appropriate since we do not have any main precept about "large", there are a larger data than the number of unemployed people. Other is, you can simply write the given exact data, that is 16,235 since it written clearly.
On the other hand those who have completed master degree were relatively less jobless , about 1
625 found to be unemployed.
Do not forget the comma.
who got bachelor and master degree opted higher
Overall, you should make a better grouping for your data. You can compare the greatest data first, then the smallest data. After that you can make the comparison of the similar data. It will make your writing easier to read and be understood.