For privacy, no Bitcoin investors would tell you that how many bitcoin they have so if you do any survey, you will likely receive fake answers with no accurate and honest figures.

Even someone answers your question honestly, your question is not too relevant so it won't be helpful for your data collection and data analysis later. A person possibly has different bitcoin number in the past, the present and the future.

Hopefully until now, you see that how bad your question is and how you need to change your current question to a better one.