://.salary.sg/2017/graduate-employment-survey-2016-published-2017/
://pay.sgcharts.com/

There are plenty of resources out there to get you a good sense of the starting salaries of graduates, the operative word being "starting".

Success in life is one that has many variables and in my opinion, your basic degree's impact tend to lessen over time to degrees. Computing some kind of ROI is simply a fool's errand.