Are you blue? Da Ba Dee Da Ba Da? In the Netherlands almost 20% of all adults (18 - 64 years old) will become depressed during their lifetimes. For minors this percentage is at 4%. That’s a lot of people. And undiagnosed depressions aren’t even taken into account. Everyone seems to be able to become depressed. Sometimes even out of the blue. The rose-tinted glasses that so many people view life through, is a shade of blue for many others.