The average health savings account balance stood at $1,561 in January, up 13% from the average recorded a year earlier.

Account growth was relatively low partly because about 18% of HSAs took in no contributions in 2008, according to Red Gillen, a senior analyst at Celent L.L.C., Boston.

The high percentage of “unfunded accounts” was also due to the fact that many HSAs started up in January 2009, and to some banks’ failure to purge inactive accounts in a systematic fashion, Gillen writes in a new Celent HSA report.

Other HSA market findings:

- HSA holders are making 66% of payments with debit cards and 20% with checks.

- The average collected monthly HSA account fee is about $2.