The percentage of U.S. short-term disability plans that rely partly or entirely on employee premium payments increased to 55% in 2006, from 19% in 2001.

Researchers at Unum Group Corp., Chattanooga, Tenn., have published that figure, based on Unum’s own data, in the company’s 2008 benefits buyer study.

Elsewhere in the study, the researchers say that health care and social assistance employers accounted for 31% of Unum in-force voluntary plan customers in 2007, and that manufacturing and construction employers accounted for 22% of in-force voluntary plan customers.

Women held 55% of the voluntary life policies, 61% of the voluntary critical illness policies and 69% of the voluntary disability policies, the researchers report.