AP Images for Humana, File, Doug Benc
In this Jan. 14, 2014 file photo, former President Bill Clinton, listens to other speakers at the Clinton Foundation Health Matters Conference, “Activating Wellness in Every Generation” panel, in La Quinta, Calif. Clinton's foundation releases is to release its annual tax documents Wednesday, Nov. 19, 2014.

LITTLE ROCK, Ark. — Contributions and grants to the tax-exempt foundation that former President Bill Clinton operates with his family grew nearly threefold between 2012 and 2013, backed by its merger with another of his charities, the establishment of an endowment and large donations from nine unspecified donors, tax records show.

The Bill, Hillary and Chelsea Clinton Foundation released its tax documents to The Associated Press on Wednesday, revealing $144.4 million in contributions and grants during 2013, up from $51.5 million in the previous year.

"In 2013 the Foundation reconsolidated the Clinton Global Initiative into its operations. As such, the ... tax document shows a corresponding increase in both revenue and expenses," the foundation's chief financial officer, Andrew Kessel, said in a statement.

Kessel also said the foundation in 2013 began raising money for an endowment to benefit current programs and expand into new areas.

"We are incredibly proud of our work helping people live their best life stories," he said. "With an even stronger financial situation in 2013, the Clinton Foundation is positioned to broaden its impact across the globe."

A separate filing by the Clinton Health Access Initiative, which is supported by the foundation and dedicated to improving health care systems in developing countries, listed expenses of $106 million for the year. Of that amount, $53 million was spent in sub-Saharan Africa and $11 million in eastern Asia and the Pacific, all for health programs.

The William J. Clinton Foundation changed its name during 2013 to the Bill, Hillary and Chelsea Clinton Foundation after the ex-president's wife stopped serving as secretary of state.

While the merger of the Clinton Global Initiative resulted in additional revenue, plus $23.7 million in expenses, the bulk of the funding increase was tied to the endowment, the foundation said in an unsigned statement.

Itemizations show that nine donors gave a total of $64 million — including four who each gave $9.9 million or more. One person donated $15 million. The names of all nine were blacked out on the IRS form; tax-exempt groups don't have to list their donors.

The Clinton Foundation does reveal who gives it money but not by specific amounts. According to data from the foundation website, 12 of last year's donors were among groups and individuals who have given $5 million or more since 1997.

The financial documents showed that $8.4 million spent on travel during 2013 totaled nearly 10 percent of the foundation's $84.6 million in expenses. A year earlier, travel made up 7.7 percent of the foundation's $58.7 million in expenses.

The foundation said the total was not out of the ordinary.

"The Clinton Foundation has a large global footprint — conducting operations in over 25 countries, and programs and commitments that reach over 180 countries," it said.