DES MOINES, Iowa (AP) — A group of Iowa casinos wants to make their annual audits confidential and stop releasing them to the public.

The Des Moines Register reports (http://dmreg.co/2hzpjHL ) that 16 of the 19 state-regulated Iowa casinos have joined a lawsuit challenging the release of those financial records.

Wes Ehrecke, president of the Iowa Gaming Association, says the audits include trade secrets that shouldn’t be released publicly.

But the reports have long been public in Iowa, and they are relied upon to gauge the health of the industry. Last year, Iowa’s casinos paid over $312 million in gambling taxes and contributed nearly $40 million to charities.

The groups that rely on charitable contributions from casinos or gambling taxes have a particular interest in the financial reports.