If you look at the actual legislative text of the final version of the Patient Protection & Affordable Care Act (PPACA, or simply ACA), the table describing the applicable maximum percentage of income that exchange-based enrollees have to pay for their premiums looks like the table below:

(Notably missing is the lower-bound 100% FPL subsidy eligibility cut-off; there's a separate section of the law which notes the 100% threshold but makes an exception for certain lawfully-present immigrants who earn less than 100% FPL but who aren't eligible for Medicaid for various reasons and are given an exception).