There have been five spaceworthy space shuttles (Columbia, Challenger, Discovery, Atlantis, and Endeavor) and two have been lost. That's an equipment loss rate of 40%.
I think this latest mission is the 26th mission of the space shuttle program. The two losses result in a ~4% mission loss rate.
The number of Shuttle missions flown is over 100, around 108 I think.
Other than those 5, the only other one in existance is Enterprise, correct?
I still don't understand why they just threw her in a closet after flight tests..all the others have been refit over time, why not the prototype?