Maybe for the world, but you're not getting an equal sample from all of the countries in the world either. Some countries, I would imagine, have a higher percentage of pets than others, and there are probably a couple countries that you get more of your answers from.
I'm just saying - there are a lot of factors involved when testing a theory. It's not as simple as throwing a question out there and counting up the answers. Feel free to do so, just realize that it won't give you a scientific fact as a result.