Through the websites of German universities that are supose to offer such programs and the number of accepted applications in these programs

Dear Nayan kadam

My suggestion is go to Coursera and Edx websites several courses relating to your area is available select such courses with verifiable certificate issued by renowned universities

If I ware you , I could have conducted Google survey among the corresponding university

Dear Nayan,

Easily search DAAD (Deutscher Akademischer Austauschdienst (German: German Academic Exchange Service) on google & you can visit their website & contact them.

This institute may help you through the information & statistics you've asking for.

good luck

Ray

I agree with Mr.Anjay kumar Mishra

I think its useful in such cases

Check all the websites will be so taime consuming for you; DAAD and st. Google is the best for your research

Dear Nayan,

The size of the market depends on relative quality and relative price. The lower the price for participating students, the higher is the potential market size for the given quality level.

Success!