NEW YORK (CNNMoney) -- Credit unions hit a record number of members last year, as a growing number of consumers grew fed up with the fees at the nation's biggest banks and took their money elsewhere.

Credit unions added 1.3 million new customers in 2011, bringing total membership to a record 91.8 million by the end of the year, according to data collected by the National Credit Union Administration from the nation's 7,094 federally-insured credit unions.









Membership refers to the number of new customers, not the number of accounts being opened.

Much of this growth came in the fourth quarter of the year, as consumer movements like Bank Transfer Day spurred customers to ditch their big banks and look for alternatives like community banks and credit unions, which tend to incur fewer fees and offer better rates.

Many consumers had already grown increasingly aggravated by new and higher fees popping up on checking accounts at banks like Wells Fargo (WFC, Fortune 500), Citi (C, Fortune 500) and Chase (JPM, Fortune 500) during the year. So, when Bank of America (BAC, Fortune 500) announced in September that it would introduce a monthly fee for debit card use, it was the last straw.

Even though Bank of America later changed its mind and scrapped its plans for the new fee, consumers were already on the move.

In the fourth quarter, following Bank of America's retraction of its fee, credit unions added 398,000 customers -- about 30% of the total new customers added during the year. A year earlier, credit unions had shed 251,000 members during the fourth quarter.

Along with membership, credit unions saw assets and accounts increase both during the year and quarter.

Total assets increased by $47.4 billion, or 5%, to $961.8 billion in 2011, boosted by $10.6 billion in new assets in the fourth quarter alone. Lending increased 1.2% during the year, bringing total loans to $571.5 billion by the end of the year -- and two-thirds of that growth occurred in the last quarter. Industry earnings also improved significantly, with net income at credit unions jumping more than 40% in 2011 to $6.4 billion.

"In the last quarter of 2011, the credit union industry grew to record levels in total assets and members," said NCUA Board Chairman Debbie Matz. "Combined with a year-over-year jump in industry net income of more than 40 percent, it appears that credit unions have turned a corner and begun to put the most severe economic crisis in three generations behind them."

The positive results came despite a decline in the number of federally-insured credit unions, which shrunk by 245 institutions to 7,094 at the end of 2011.

A separate report from J.D. Power and Associates that came out earlier this week showed a similar exodus from big banks to smaller institutions.

While the rate of customers leaving small institutions over the past year declined significantly, bigger banks saw an increase in the percentage of customers who jumped ship, according to J.D. Power's survey of more than 5,000 customers who shopped for a new bank or account over the past 12 months.

The defection rate for large, regional and midsize banks averaged between 10% and 11.3% last year (up from 7.4% to 9.8% in 2010), while the defection rates for small banks and credit unions averaged only 0.9% -- down significantly from 8.8% in 2010.