Starbucks Corp. customers loaded more than $1.5 billion on to the company's loyalty cards in its fiscal year, up 20% from last year. Nearly one in five of its customers uses a loyalty card to pay for transactions, Starbucks said.

"Growth in our Starbucks card business continues to accelerate at record rates," Howard Schultz, Starbucks' chairman, president and chief executive, told analysts on a conference call Thursday to discuss earnings.

Nearly 2 million customers to date have joined its Starbucks Rewards program, and more than 1.25 million of those have reached the top "gold" level by making at least 30 purchases, Schultz said.

Starbucks introduced its rewards program in 2008. It retooled the program earlier this year, adding the "gold" perk, which awards customers with a free drink for every 15th purchase.

Starbucks said its income rose 86%, to $278.9 million for its fourth quarter that ended Oct. 3 from a year earlier. Total net revenue increased 17.4% year over year, to $2.84 billion.

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