Animation Exit Time

So I see that animation Exit time works in the percentage of the animation length...but what if I dont know how long i want the animation to last? In my case i have a character that is jumping, whenever he is in the air the 'Jump" animation will be active, but it is not a simple jump, there is also a double jump, fast fall, dash and other stuff, therefore it is basically impossible for me to know the exact time as to when the character will reach the ground again, and i can stop the 'Jump' animation. Is there a way to make the Exit time condition in the animator a variable? For example Exit time = isGrounded, that way the animation will only stop if the character is grounded? Or is there another way to manouver through this?

 

That's what animation parameters are for:

http://unity3d.com/learn/tutorials/modules/beginner/animation/animator-scripting