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For the third year in a row, Weston, Fla.-based Ultimate Software tops Fortune's "best workplace for millennials" list.

"According to our surveys, 98% of Ultimate's millennial employees say they are experiencing a great place to work," said Michael Bush, CEO of Great Place to Work, a research group that compiles the annual list with Fortune magazine.

The rankings are determined by anonymous employee survey feedback on how much workers trust company leaders, whether people are treated with respect, fairness of workplace decisions, and camaraderie in the workplace.

The software development company attributes the ranking to its "people first" culture, which includes a wide range of employee benefits including 100% paid health insurance premiums. Unusual benefits include coverage of in vitro fertilization treatments for women wanting to become pregnant, gender reassignment coverage, and $10,000 in financial assistance to legally adopt a child.

Fortune's top 10 on the "best workplace for millennials" list also included, in order: Salesforce, Edward Jones brokerage, Workday, Kimley-Horn, Power Home Remodeling, Veterans United Home Loans, Hyatt Hotels Corp., Kimpton Hotels & Restaurants and Progressive Insurance.

Other Florida companies that made the top 100 are: construction firm Moss; auto-related business JM Family Enterprises; IT security firm KnowBe4; Publix Super Markets; and construction and real estate firm Avesta.

The millennial generation, born 1981 and 1996, are as young as 23 and turn as old as 38 this year, according to Pew Research Center.