(NASDAQ:

) and

(NASDAQ:

) lower-cost tablets have been unable to thwart the

(NASDAQ:

) empire. According to

, the 2013 Nexus 7 and Kindle Fire HDX have fallen below shipment expectations. This might be why Amazon has stopped talking about its market share in the United States. To be fair, the company has not provided an update

. But if the Kindle Fire has garnered

than the 22 percent share it had two years ago, Amazon would likely want to tell investors about its growth. Without any official sales updates, it is impossible to determine how the Kindle Fire is performing at retail. Likewise, Google has been reluctant to reveal sales of the second-generation Nexus 7. Some reports claim that the company could ship as many as

in 2013. Others claim that the number could be limited to

. In either case, Apple would still sell

than Google could

in an entire year. DigiTimes' sources (from supply chain makers in Taiwan, as usual) claim that Apple's tablets are the reason for Google and Amazon's decline. The newly announced iPad Air -- which is

and is

than the iPad 3 -- seems to be having a negative impact on the competition.

The iPad Mini with Retina Display is expected to deal another blow to competitors when it is released later this month, though its price ($399) could keep it from attracting cost-conscious consumers. Apple does not need to win over those customers, however. The company seems to be perfectly content producing premium-priced products, even if it means sacrificing a few sales in the process. This is why the iPhone 5C retails for $549 --

. Disclosure: