The WNBA players' union announced Thursday it would opt out of the league’s collective bargaining agreement after the 2019 season, starting the clock early for negotiations with the league over a larger slice of revenue and financial transparency.

The 12-team league has been around for 22 years and has lost money in each of those years, according to estimates from the NBA, which owns 70 percent of the women’s association. In 2017, the league operated at a $12 million loss.

Under the current labor deal, players make a base salary of between $39,000 and $115,000 per season excluding incentives and benefits. Academic studies state the league pays players roughly 20 percent of total revenue. The NBA pays players about half of league revenue, or about $3 billion.

The WNBA rarely shares concrete financial information, even with players, one of the main sticking points that led players to leave the current agreement.

“In opting out of this CBA, our primary objective is full transparency,” players' union President and Los Angeles Sparks forward Nneka Ogwumike wrote in the Players' Tribune announcing the decision. "We just want information about where the league is as a business, so that we can come together and make sound decisions for the future of the game.

“You probably don’t know this, but as players, we never get to see the numbers. We don’t know how the league is doing.”

But Mark Tatum, the NBA’s deputy commissioner and chief operating officer, said Thursday on ESPN’s “Outside the Lines” program that the league has shared financial information with the players' union. Tatum is overseeing the league on an interim basis after the October resignation of WNBA President Lisa Borders.

“The Players' Association has all of those financials,” he said. “They have access to that. We’ve shared it with them, and what we are looking forward to doing is having a fully open, transparent and engaging discussion around the business realities that exist in the league.”

The current deal was set to expire in October 2021, but opting out allows negotiations to start now and a new agreement can take effect in the 2020 season.

“The league and its teams are committed to an open and good-faith negotiation that is rooted in the financial realities of our business," Tatum said in a statement. "We are getting to work immediately and are confident such a process can lead to a fair deal for all involved.”

Players and WNBA and NBA higher-ups have long been at odds over the league’s pay scale and marketing investment. Players contend a salary bump and increased resources for exposure will help the WNBA reach a larger audience and boost the women’s game’s finances.

“We have a great product as a league and don’t get the support and coverage we deserve,” Washington Mystics forward Elena Delle Donne tweeted in April. “... We absolutely do not get promoted as our counterparts do. Yes, I’m talking about the NBA.”

League executives have responded that those kind of increases do not make financial sense for a business that continually operates in the red.

“As much as we’ve done in lending the league our name,” NBA Commissioner Adam Silver said to the New York Times in 2015, “the people who have been in the sports business for a long time, and I’m one of them, historically underestimated the marketing it takes to launch a new property.”

Amid that tension, the league has seen recent signs of commercial success.

Attendance grew in 2016 and 2017 before a 13 percent drop in 2018. But viewership increased for game broadcasts on ESPN networks and NBA TV, according to the league, and it began live-streaming games on Twitter. WNBA teams and players also appeared on a video game for the first time with the release of NBA Live 18.

Read more from The Post: