Singapore is included in how they determined this result, therefore you shouldn't use this result to explain why singapore is doing better.

No, Singapore is not in China and is thus not in the set of "100 Chinese cities". It's only mentioned in the paper in graphs of temperature and humidity of a whole bunch of countries.

Ah fair enough. I guess we'll have to observe areas with similar climates and see if it holds. If so, I'm taking that tropical cruise after all. ;)