SFO: what changed

Count destinations flown to at least once12 times52 times365 times in a year.

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Show destinationsairlines that were droppedaddedkept.

Every count is of flights departing from SFO: routes are one-way. A destination is dropped when flights to it stopped or fell below the minimum, not when a particular flight number ended. Airlines are counted as groups, so a merged airline's flying is counted together; more on how airlines are grouped.