The number of companies earning top marks for how they treat their lesbian, gay, bisexual and transgender employees has hit a record high, according to a new report released Monday by the Human Rights Campaign (HRC), the nation's largest LGBT rights advocate.

HRC's 15th annual Corporate Equality Index (CEI) ranks 517 major companies with a perfect score of 100, a 25 percent increase from last year and the largest single-year jump in the report's history.

“Even in the face of relentless attempts to undermine equality, America’s leading companies and law firms remain steadfast and committed to supporting and defending the rights and dignity of LGBTQ people,” said HRC President Chad Griffin in announcing the results. “The unprecedented expansion of inclusive workplaces across the country and around the globe not only reflects our progress, it helps drive it. As we enter a new chapter in our fight for equality, support from the business community will be more critical than ever to protect our historic advancements over the last decade and to continue to push equality forward for workers, customers, and families around the world.”

Twelve of the top 20 Fortune-ranked companies received perfect ratings, including Wal-Mart, Chevron, Apple, General Motors, General Electric, Ford Motor Company, CVS, McKesson, AT&T, Verizon, Fannie Mae and HP.

Edward Jones, Delta, Netflix, Hasbro, Tyson and Crate & Barrel were among the companies to receive a perfect score for the first time. Apple and Xerox are among the companies that have consistently scored high marks since the survey's introduction in 2002.