I always find these threads a bit eyebrow-raising; everyone always seems surprisingly strong. I bicep curl 17.5 kg on each arm, currently performing about 7/8 reps. of this, which seems to pale in comparison to most posters, yet I'm fairly confident that I'm considered muscular. Yet, I feel like a weakling, whenever I read threads such as this; either there're a Hell of a lot of beefcakes about, or something's a bit fishy. I am confident that I have perfect technique, though; my arms remain firmly locked by my side, so my body doesn't assist in the lifting, in any way. What I find odd, is how I even see muscular guys, at the gym, who seem to be using their bodies to assist them, when lifting weights. It's true about machine performances being misleading; I've used various machines, for the seated chest press, say, and may find myself being able to do 6-8 reps. of 105 kg on one machine, but only 63 kg, on another. I've been working out for four years, but sporadically, and I didn't initially adhere to the right diet; more recently, I've been taking it more seriously, but alcohol consumption (and the associated lack of appetite, the following day) has always tainted my progress, somewhat.
Technically, the answers to be given to the poll, depend on whether or not it means with both arms combined, or on each arm, individually. I voted '15-20', but that represents what I can do on each arm. The 70+ lot are a curious bunch, in my mind.
As another interesting question: How much do everyone's biceps/arms measure, when flexed (but not after a workout)? Mine were a tad over 15 inches, at last measurement, but may have increased slightly, since.