its not 75-80% it all 100% Muslims are converts. From ME/Americas/APs .. all of the people are converts. Even today after so many propogandas even almost 20000 Americans are turning towards Islam every year. None of them are being forced.
As per Indian history goes other than in case of Aurangjeb not even staunch anti-Muslim historians have written that Islam was being spread by sword in India. well if you have been studying in a RSS school that is a different story then ...