1% is because 90% of the elves DIED when Silvermoon got sacked by Arthas.
You know, they all died right? 9% became bloodelves. 1% became high elves.
90% of 10% is 9% leaving 1%.
There are more tigers in our real life planet, than there are blue eyed elves in WoW. They are beyond endangered. They are essentially extinct. Blizzard has no reason to put extinct races into their game as playable.