More than two years after Scott Walker’s showdown with organized labor in Wisconsin, the official numbers for the state’s public sector union membership are in — and they are down. Way down.

According a Labor Department filing made last week, membership at Wisconsin’s American Federation of State, County and Municipal Employees Council 40 — one of AFSCME’s four branches in the state — has gone from the 31,730 it reported in 2011, to 29,777 in 2012, to just 20,488 now. That’s a drop of more than 11,000 — about a third — in just two years. The council represents city and county employees outside of Milwaukee County and child care workers across Wisconsin.

Labor Department filings also show that Wisconsin’s AFSCME Council 48, which represents city and county workers in Milwaukee County, went from 9,043 members in 2011, to 6,046 in 2012, to just 3,498 now.

These numbers come from the locals’ LM-2 filings, annual reports they must make to Labor Department. They can be found here.

They show why the state worker unions and their liberal allies fought such a protracted, bitter battle in 2011 over Republican Gov. Scott Walker’s changes to the state’s labor laws. Under the old laws, state employees were obligated to pay dues to a union even if that worker didn’t want to belong to a union. Walker changed that to allow state workers to opt out of paying those dues. He also required unions to submit to an annual re-certification vote. Without those requirements, the unions have found it much harder to retain members.

Neither council responded to a request for comment. The numbers have to sting given that AFSCME was founded in Wisconsin.

The Labor Department filings don’t paint of a complete picture of ASFCME in Wisconsin. It has two other branches in the state, Council 24 and Council 11, but they do not have to file these reports. According to a Labor Department spokesman, these federal disclosure requirements do not extend to unions that solely represent state and local government employees. Councils 40 and 48 must make the filings because they represent some private sector employees. The other two do not.

Still, the filings do confirm earlier reports that the union’s overall membership has fallen in the Badger State. Last year, the Wall Street Journal reported that statewide membership “fell to 28,745 in February from 62,818 in March 2011, according to a person who has viewed AFSCME’s figures.” A union official disputed the figures  to me at the time but refused to provide their own numbers.

Other public sector unions in the state haven’t suffered much. American Federation of Government Employees Local 45 reported to the Labor Department last month that its membership was 4,362. That is up slightly from 4,256 in 2012 and 4,236 in 2011.