FORTUNE -- The good news for Apple (aapl) in a report issued Thursday by the NPD Group is that it still owns the biggest share of the richest and most profitable segment of the U.S. smartphone market.
One third of Apple's U.S. sales in 2013 were to Americans making more than $100,000 a year, and of that group, Apple's share was 65%, according to NPD (which did not provide a spreadsheet supporting that number).
The bad news is that the cream of the U.S. market is also the segment that is growing most slowly -- only 4% year over year according to NPD.
The fastest growing segment -- people making under $30,000 a year -- grew at 42% a year, double the industry rate. Only 20% iPhone sales went to that segment of the market, compared with 35% for Samsung.
“With the fastest growing segments of the industry in the lowest income demographics, both Apple and Samsung face challenges in 2014,” said NPD's Stephen Baker in Thursday's press release. “For Samsung this demographic is likely to be the most competitive segment of the market in 2014 and they have a very high dependency on sales here. Apple has the opposite problem of gaining share in the fast growing entry-level market while still maintaining its position as the dominant supplier to affluent consumers.”
CORRECTION: An earlier version of this story had the wrong income level in the headline. According to NPD, Apple has 65% of the $100,000+ per year market, not $60,000+ plus.