The world's highest-paid actress Jennifer Lawrence admits she struggles to negotiate her salary - especially compared to men

Jennifer Lawrence is the world's highest paid actress. But her high salary, which Forbes estimates was $52 million in 2014, pales in comparison to the world's highest paid actor, Robert Downey Jr., who raked in an estimated $80 million.

Lawrence realized she was underpaid when emails unearthed during the Sony hack revealed that she and Amy Adams were only offered 7% of proceeds from their movie, "American Hustle," while the male actors (Christian Bale and Bradley Cooper) and director were offered 9%. Initially, the leak email said, Lawrence was only offered 5%.

The actress has written an op-ed about why her salary is less than her male counterparts in Hollywood. She says she wrestles with not wanting to sound whiny, and as a result she doesn't demand as much as she should during negotiations.

"When the Sony hack happened and I found out how much less I was being paid than the lucky people with dicks, I didn't get mad at Sony. I got mad at myself," Lawrence writes. "I failed as a negotiator because I gave up early. I didn't want to keep fighting over millions of dollars that, frankly, due to two franchises, I don't need."

Lawrence wondered if being a woman made her less confident about standing up for herself and her compensation.

"If I'm honest with myself, I would be lying if I didn't say there was an element of wanting to be liked that influenced my decision to close the deal without a real fight. I didn't want to seem 'difficult' or 'spoiled,'" she writes. (Fellow actress Angelina Jolie was referred to as spoiled in another Sony leaked email).

"This could be a young-person thing. It could be a personality thing. I'm sure it's both. But ... based on the statistics, I don't think I'm the only woman with this issue. Are we socially conditioned to behave this way? ... Could there still be a lingering habit of trying to express our opinions in a certain way that doesn't 'offend' or 'scare' men?"

You can read Lawrence's whole letter, titled "Why do I make less than my male co-stars?" here.