Anybody can look up what their PPACA premiums would be today, here;
https://www.healthcare.gov/see-plans/
You can easily look up what today's unsubsidized premiums are on the Premera (Alaska) website;
https://www.premera.com/ak/visitor/shop-for-plans/individual-and-family-plans/health-plans/
If you follow Dermot's link to the KFF.org page, you will find KFF's usual completely thorough documentation. Keep in mind that there are several different geographic insurance premium zones in Alaska. Generally speaking, today if one's household income is less than 400% of Alaska poverty line for a given household size, then a subsidy will reduce the premium cost down to 9.5% of household income or less. It looks like KFF is using data for today's silver plan, then applying this bill's new increased old age penalty and the reduced subsidies. By the way, KFF.org has been a respected resource for US health and health insurance data since the late 1940's, and is independent of Kaiser healthcare.