The number of Iowans who are members of labor unions dropped sharply in 2017, according to new estimates from the federal government.The decline comes a year after the Republican-controlled Iowa Legislature significantly reduced the collective bargaining rights of most public sector workers in the state.The federal Bureau of Labor Statistics reported last week that 104,000 Iowans were members of labor unions in 2017, down from 129,000 the year before.It estimated 7 percent of wage and salaried workers in the state belonged to unions in 2017, down from 8.9 percent the year before.The figures, which account for both public and private sector unions, aren’t exact totals but estimates derived from a survey of a quarter of 60,000 nationwide households that take part in the government’s monthly Current Population Survey.This isn’t the first decline in union membership in recent years.