I cannot remember exact number. But every single one of them was within .1 volt of the min (some were even outside of specs) I had designed for "typical" and had to end up squeezing in an extra LED.
I was a little dissapointed, since this would indicate they were a low bin unit, and will place you low on the watts/current curve.
I really haven't had a chance to do a decent comparison test on the 660nms.