It was in early 2021 that Congressional Democrats passed & President Biden signed the American Rescue Plan Act (ARPA), which among other things dramatically expanded & enhanced the original premium subsidy formula of the Affordable Care Act, finally bringing the financial aid sliding income scale up to the level it should have been in the first place over a decade earlier.
In addition to beefing up the subsidies along the entire 100 - 400% Federal Poverty Level (FPL) income scale, the ARPA also eliminated the much-maligned "Subsidy Cliff" at 400% FPL, wherein a household earning even $1 more than that had all premium subsidies cut off immediately, requiring middle-class families to pay full price for individual market health insurance policies.
Here's what the original ACA premium subsidy formula looked like compared to the current, enhanced subsidy formula:
South Dakota has around ~54,000 residents enrolled in ACA exchange plans, 94% of whom are currently subsidized. I estimate they also have another ~3,000 unsubsidized off-exchange enrollees.
Vermont has around ~32,000 residents enrolled in ACA exchange plans, 93% of whom are currently subsidized. I estimate they also have another ~2,000 unsubsidized off-exchange enrollees.
Combined, that's ~35,000 people, although the official carrier rate filings claim it's more like 36,000 statewide.
Washington State has around ~308,000 residents enrolled in ACA exchange plans, 73% of whom are currently subsidized. I estimate they also have another ~29,000 unsubsidized off-exchange enrollees.
Tennessee has around ~642,000 residents enrolled in ACA exchange plans, 95% of whom are currently subsidized. I estimate they also have another ~9,000 unsubsidized off-exchange enrollees.
Utah has around ~421,000 residents enrolled in ACA exchange plans, 95% of whom are currently subsidized. I estimate they also have another ~17,000 unsubsidized off-exchange enrollees.
Rhode Island has around ~42,000 residents enrolled in ACA exchange plans, 88% of whom are currently subsidized. I estimate they also have another ~3,000 unsubsidized off-exchange enrollees.
West Virginia has ~67,000 residents enrolled in ACA exchange plans, 97% of whom are currently subsidized. They also have an unknown number of off-exchange enrollees (likely only a few thousand at most).
New Jersey has around ~513,000 residents enrolled in ACA exchange plans, 85% of whom are currently subsidized. I estimate they also have another ~76,000 unsubsidized off-exchange enrollees.
Illinois has around ~466,000 residents enrolled in ACA exchange plans, 90% of whom are currently subsidized. I estimate they also have another ~57,000 unsubsidized off-exchange enrollees.