There is again a bug in the number of streets in some cities, for example in this Belgian city of Watermael-Boitsfort - Watermaal-Bosvoorde:
- there are 260 streets indicated below the name of the city
- there are only 234 streets in the city (see e.g. the list of my completed and incomplete streets there: https://citystrides.com/users/788/cities/29736), This figure is used to calculate the percentages.
The later seems to be correct unless by accident you excluded some streets, the former seems to be the problematic one, maybe because the count includes objects which are not streets, or has not been updated. The difference is usually not big (1-2 streets), but for some, like the example above, it is bigger. Based on the Brussels sample - it looks like the difference is more pronounced for the cities with large nature areas, so maybe hiking trails/paths are the cause for the difference?
This is a very minor issue, as percentages seem to be calculated correctly, unless this is is the result of some streets missing from your data