TERRE HAUTE, Ind. (AP): Retirements and changes in the public sector have driven Indiana’s union membership to its lowest level in more than two decades.

The Bureau of Labor Statistics shows union members made up 9.1 percent of Indiana’s workforce in 2012. That’s down from 22 percent in 1983 and marks the first time since the government started tracking individual states in 1989 that Indiana’s union workforce has fallen below 10 percent.

Experts say Governor Mitch Daniels’ decision to end collective bargaining for state workers in 2005 contributed to the drop. They say the effects of Indiana’s right-to-work law barring companies from requiring union membership haven’t been fully felt yet.

University of Illinois labor professor Robert Bruno says membership could rebound if the nation’s economy continues to struggle.