Refer to the figure showing the results of Bjorkman and colleagues' studies of plant responses to different light levels. The plants were reared at three different levels of light intensity: high (red line), medium (blue line), and low (green line). The acclimatized plants were then subjected to various light levels, and their ability to photosynthesize was measured.

-At approximately what light intensity level are the plants acclimatized to high-intensity light photosynthesizing at twice the rate of those plants acclimatized to low-intensity light?