The graph of same amplitudes is called a normalized view, the peak of the three graphs is multiplied to 1.0... It doesn't really matter about the individual cone/rod efficiency because there are different counts and ratios of them as necessary.
The relative spectral sensitivities of the five photoreceptors in human retina, including S-, M-, L-cones, rods, and ipRGCs (A), LED spectral distributions (B), and LED chromaticities in CIE color space. (ref 2015)
Scientists use spectral photometry of cells and measure their response, so that's the field you can study to know the spectral sensitivity.
The brain/ganglions can adjust for differences to give a balanced/optimized mix, and there can be 2 times more of a specific receptor cell type if it 0.5 times as receptive, so the perceived view is more or less psycho-normalized to see white accurately.
Current understanding is that the 6 to 7 million cones can be divided into
- "red" cones (64%),
- "green" cones (32%),
- "blue" cones (2%)
based on measured response curves. They provide the eye's color sensitivity. The green and red cones are concentrated in the fovea centralis . The "blue" cones have the highest sensitivity and are mostly found outside the fovea, leading to some distinctions in the eye's blue perception.
The cones are less sensitive to light than the rods, as shown a typical day-night comparison. The daylight vision (cone vision) adapts much more rapidly to changing light levels, adjusting to a change like coming indoors out of sunlight in a few seconds. Like all neurons, the cones fire to produce an electrical impulse on the nerve fiber and then must reset to fire again. The light adaption is thought to occur by adjusting this reset time.
The cones are responsible for all high resolution vision. The eye moves continually to keep the light from the object of interest falling on the fovea centralis where the bulk of the cones reside.