Low intl pax demand from Rio (SBGL/GIG)

[SteveHunt]

I have noticed that Rio has low pax demand to major international destinations, compared with Sao Paulo (SBGR/GRU), or even Lima (SPIM/LIM). Granted, Rio (metro area pop: 11m) is smaller than Sao Paulo (pop: 20m), but it is larger than Lima (pop: 8.5m).

Examples:

From	To	Demand
JFK	GIG	74
JFK	GRU	190
JFK	LIM	140
MIA	GIG	85
MIA	GRU	320
MIA	LIM	160
CDG	GIG	110
CDG	GRU	270
CDG	LIM	180

How did the demand calculation return such an unusual result? Is there something about GIG (e.g. max landings per hour) that causes this?