SWA was founded in 1971, just over 35 years ago. SWA has been profitable at least 30 of those 35 years or 86% of the time.
Actually 33 out of 35 years since they started flying -- every single year since 1973. Also profitable for 62 consecutive quarters going back to the Gulf War in early 1991. And, for what it's worth, Southwest's fleet is now larger than United's.