Like I said, there’s a cultural and linguistic dimension to what constitutes as ‘dark’ or ‘pale’. Certain languages like French, Portuguese, Irish, Russian and Polish have separate words for the colour red and red hair respectively. What the Germans call ‘rotfuchs’ is the French ‘renard roux’. (Portuguese however almost always reserves ‘ruivo’ for humans.)
Conversely speaking, what is ‘blond’ is another ‘brown’. I suspected that would’ve complicated things when it comes to making objective hair colour percentages. There is no doubt an association with fair hair and youth but this is usually applicable for Europeans as the association’s absent elsewhere.
There’s one study that involved surveying hair colours among men and women. Except for a few deviations in the Iceland replication group, women were more likely to have darker hair and eyes than men do. Some suspected that many more women are more likely to dye their hair, thus skewing results.