A report by ABI Research shows that Apple's tablet market share has dropped to 55%, the lowest since the iPad was released.
http://www.notebookcheck.net/Apple-iPad-family-declines-in-market-share.84646.0.html
The Black Friday sale figure may not be seen as a strong indicator to iPad's popularity. The policy of Apple is that its product will never decline in price (through its own online/shopfront and contracting with resellers) until the next generation comes out. The only exception being Black Friday which every product will receive a 10% discount. If we take into account the consumer's tendency to "pick the better bargain" they will certainly go for Apple on Black Friday as they cannot get such discount in the rest of the year. Android tablets, while increasingly popular, still suffer from the normal price deterioration once they enter the market. The occasions of obtaining them at a lesser premium are far more common and not confined to Black Friday. It is thus of no wonder why iPad accounts for the majority of sale on Black Friday.