Everyone differs. by how much that depends on if you mean number of hairs or overall mass which may be affected by both the number of hairs and the diameter of each individual hair.
Hair color has absolutely NOTHING to do with the NUMBER of hairs. No on can tell you how many hairs you have either, so I suggest you get to counting! :)
It is impossible to count your hairs no mater what anybody says and if you try um.. your hair will keep growing and you will loose count the minute you miss one little hair your whole count is wrong...