Each plan has a different scheme for age-related increases - some never go up, some go up until a certain age then stop, some are treated as a discount from the full rate (which you start paying at a designated age), and some go up for ever. (When we chose our supplement plan, I plotted the age-related cost of every plan available out until age 100). Check your plan - you may have an end-date on the age-related increases.

There's a second increase that isn't fixed (isn't age-related, and can happen every year forever) - that's cost of medical care overall increase. Anyone currently shopping can check with their state SHIIP office and get the information on each supplement plan for the last 3-5 years, so you can see generally which plans increase the most year over year).

My spouse's and mine went up around the same amount as yours. Most of it was due to the increase in community medical costs - and far exceeds any increase UHC has imposed over the last decade. (I suspect longer, but I'd have to check with my parents - since their experience with it goes back nearly 3 decades.)