Credit union membership and assets continued to grow, but there was a wide disparity between large and small institutions, CUNA Mutual Group reported in its June Credit Union Trends Report.

The average credit union asset growth of 7.3% in 2015 hid a disparity between large and small credit unions, CUNA Mutual said. During the past 12 months ending in the first quarter of this year, credit unions of more than $1 billion grew assets 9.2%. That compares with asset growth of 1.5% at credit unions with fewer than $20 million.

Credit union membership growth is expected to exceed 3% this year, pushing total credit union membership to 108 million members. In the last 12 months ending in the first quarter of 2016, credit union membership grew 6.6% at institutions with assets of more than $1 billion, compared with less than 1% for credit unions with fewer than $100 million.

There were 2,614 credit unions with assets of fewer than $20 million and membership at those credit unions declined 1.2%.

Savings balances grew 6.9% in 2015, but again, there were disparities between small and large credit unions. In the last 12 months ending with the first quarter of the year, credit unions with assets of more than $1 billion saw an 8.8% increase in savings balances. That compares with savings growth of 1.5% at credit unions with assets of fewer than $20 million.

CUNA Mutual Group reported that as of April, there were an estimated 6,128 credit unions in operation – a decrease of 290 during the last 12 months. That is more than the 282 annual attrition of a year ago.