Since when? We were taught that the normal temperature is 36.6. Even thermometers had such markings. and the 37.0 was marked red, because there the range of "something is wrong" started.
In the USA it's 98.6 F. I just converted it to Celsius and it comes to 37.0. It's interesting it's different in different places. (That's probably also why Europeans are so cold and snobbish... I kid, I kid)