my first idea was to use statistical information from, for example, statista, but it appears to be very difficult to find reliable data (revenues, etc.). My second idea was to focus on the German population, then segment by gender and age and estimate ratios of how many people do sports and how many of those people practice Yoga. My third idea was to use the Google key word analysis to try to find out how many people look for Yoga in Germany and then estimate how many of those people actually practice Yoga already or want to practice it. None of these approaches seem sufficient, though. Maybe one of you has a more promising idea to approach this problem. Thank you in advance for your help.