This is a hard question to answer but I can give you an estimate number. Well, really hard question, indeed. I’m not a kind of person who works 11 months per year and takes 1 month to travel, therefore it’s hard to predict how much I’ll spend a year.
What I can say is, I try to travel unconventionally, which means, I do not stay in expensive hotels. I don’t eat out in fancy restaurants and I don’t buy most of the services a normal tourist would buy. I also rarely pay for accommodation. I use ‘collaborative consumption practices’ to exchange my knowledge for accommodation or food and therefore decrease my expenses. I also do volunteer work in order to contribute to a local community, but also save money with accommodation. There are tons of tricks and practices that anyone can do in order to not spend much money while travelling.