Hi!
is as follows (with some explaining comments inline):
This is very nice, thanks! Will use this as a test case for the query engine (btw yes it works on my test machine just fine :).
more than one match per city then, even with DISTINCT). Picking the current population will become easier once ranks are used more widely to mark it.
I think this is solved with preferred ranks and "truthy statements" concept pretty nice. So people should start using ranks to separate current data from historical data.