Every year StackOverflow runs a survey. This year, more developers answered more questions than ever before.
26,086 people from 157 countries participated in a 45-question survey. 6,800 identified as full-stack developers, 1,900 as mobile developers, 1,200 as front-end developers, 2 as farmers, and 12,000 as something else.
This survey has been conducted to help better understand the community and to help the community better understand itself.
These results are not unbiased. Like the results of any survey, they are skewed by selection bias, language bias, and probably a few other biases. So take this for what it is: the most comprehensive developer survey ever conducted. Or at least the only one that asks devs about tabs vs. spaces.