Loss of Lemmings: Zero
Stack exactly at the right hand end of the level bit of the hump - one pixel to the left and it will be to far to jump, one to the right and the laser will not cut through (see below). The second Lemming will get past - make it Stack just under the overhang. Make the first one a Rock Climber. When the first stack is complete, Jump the Lemming off to the right - it should clamber away over the sawtooth shapes. Stop the second stacker while facing left by trying to Shimmy. Wait for the rock climber to be transported to the bottom of the screen. Laser Blast just left of the underside of the pit into which Lemmings are being transported, so that the tiny lower chamber is breached but the laser beam stops on the steel. Stomp with one of the Lemmings in the pit on the right hand side - they should all get out to the left, and none should go right. Jump the climber onto the bottom of the chain, Fan it to full speed, and release it within the maze. It should climb round to the transporter on the right, and emerge under the left hatch horde. Laser Blast exactly at the right end of the gap in the steel, so that the first stack is completely removed.