If you thought CEOs were earning way too much while the bulk of their companies' employees got left behind -- well, you weren't wrong.

The pay gap between chief executives of major U.S. firms and their median workers is massive, according to a recent report from career review site Glassdoor , which looked at data from 2014. The average pay ratio of CEO to median worker was 204-to-1, the report found. At the top of the list, four CEOs earn more than 1,000 times the salary of their median worker.

The biggest gap was at media company Discovery Communications, where CEO David Zaslav earned $156.1 million last year, nearly 1,951 times the firm's median salary of $80,000.

Following him in the next three top slots were Chipotle boss Steve Ells, who earned $28.9 million, or 1,522 times the median salary of $19,000; CVS Health CEO Larry Merlo, whose $32.4 million pay was nearly 1,192 times that of the median worker's $27,139; and Walmart chief Doug McMillon, who made $25.6 million last year, about 1,133 times the median employee's $22,591.

Glassdoor pulled CEO salary data from Securities and Exchange Commission filings and used employees' self-reported salaries from its own site. Its report includes 441 of the S&P 500 companies.

Lawmakers are already pushing to make this issue more transparent. Earlier this month, the SEC approved a rule that would require companies to disclose the ratio of CEO pay to that of the median worker.

Income equality is likely to be a key issue in the upcoming presidential election. Vice President Joe Biden , who reportedly is considering a run in 2016, has expressed concerns in private conversations that Democratic presidential candidate Hillary Clinton may not be able to effectively back issues like economic inequality.

Another Democratic presidential hopeful, Bernie Sanders , has been forceful on the topic. The decision to require companies to disclose how much more CEOs are paid than workers is an important step in the fight against income inequality, Sanders said earlier in August of the SEC's new rule.

"I hope that shining a spotlight on the disparity will help working families, Sanders added. He has also advocated for a $15 federal minimum wage.