Question about percentage range?

Let's put our thinking caps on for a minute. So if you consider the big old sun as being 100% white, and a totally pitch black area as 0%, what would be the % range that a camera can capture as a RAW file or JPG file?

Let's say you have a 12MP camera, are there any factors which would change the percentages? Perhaps sensor size or size of lens?

From what I have noticed it seems when bracketing a shot to create an HDR photo the % range is increased from the exposed RAW or JPEG image.

Does this make any sense?

I don't know about the sun itself, but the difference between a subject in bright daylight and a subject in darkness only lit by starlight is about 22 or 23 stops. 2 to the 23rd power = 8,388,608, so bright daylight is 8.38 million times brighter than the starlit night. The difference between a subject in direct, midday sun and in deep shade (at the same time of day) is 6 to 8 stops. 2 to the 8th power is 256.

I am not sure of all the things that can influence dynamic range in a sensor, but photo-receptor size, ISO, bit depth, and processing (the characteristic curve applied) appear to. Whenever discussing dynamic range it's a good idea to define what is meant by dynamic range. Different photographers, instructors, and testers can have various definitions.

Dxomark.com defines dynamic range as "...the highest and lowest luminance values that can be accurately measured on a sensor." They say the Canon 7D and 5DII have just under 12 stops of dynamic range at ISO 100, and it begins to decline as ISO is increased. By ISO 1600 the 5DII has lost a stop of dynamic range (just under 11 stops of DR), and the 7D 2 stops (just under 10 stops of DR).

dxomark.com

Clarkvision.com defines dynamic range as "...the maximum signal divided by the noise floor at each ISO." They claim the 5DII has just under 15 stops of DR, and the 7D a bit more than 13 stops of DR.

clarkvision.com/articles/digital.sensor....e.summary/index.html

8 to 12 stops of dynamic range is a common claim for today's DSLRs. I know that if I'm facing a scene with over 8 stops difference between the shadowed areas and the lit areas I'm going to be considering ways to lessen the difference: HDR, add light, etc.... 12 stops is a difference of x4096. 8 stops is x256. So if a DSLR has 8 stops of dynamic range: 256/8,388,608=0.00003 or 0.003% of the range between brightest sunlight and darkest night.

When I was in school (film only) we were mostly concerned about usable dynamic range; defined as the difference between the highlights retaining 100% detail and the shadows retaining 100% detail. We were taught to only count on 5 stops of 100% detail in prints, so even if the sensor/film can capture more it needs to be compressed to be displayed in a print.

Well Henery pretty much covered it. The light from the sun is yellow by the way and, is coverted to white by the atmosphere. So those living closer to sea level have a whiter light, people such as myself at 8000ft is more yellow. Less atmosphere equals less conversion through filtration.
The one thing I would like to see the camera manufaturers work on is getting the cameras to keep their Dynamic Range through all of the ISO speeds.