How does Google know if a place is busy?

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Tags

1. #while
2. #transport
3. #conditions
4. #users
5. #historic
6. #sales
7. #people
8. #times
9. #might
10. #ideal
11. #feature
12. #useful
13. #analyse
14. #predicted
15. #location
16. #google
17. #normally
18. #other
19. #anonymised
20. #quiet
21. #increase
22. #searches
23. #moment
24. #generally