Yeah, I'm thinking the simpler answer here is that this data is basically trash. Based on some of the other comments in this thread, it really seems like it is not a good quality survey with pretty poor quality control.
It reports fewer agency developers in China than in Andorra. The difference between the two represents 1% of Andorra's total population and 0.7E-4% of China's.
There are for sure not 15k devs there. I’ve been to Andorra and visited a few meetups. They had very few people in attendance.