Select the fourth download - as noted above - called "National Health Expenditures by type of service and source of funds, CY 1960-2023 (ZIP)"
I opened the .xlsx, but they ship a csv too. The xlsx file shows on line 6 'Private Health Insurance' - and this is under the sub-heading 'Total National Health Expenditure', itself in the column called 'Expenditure Amount (Millions)'.
I've re-visited your earlier link - https://www.cms.gov/files/document/highlights.pdf - and can't see anything - especially 'top of the second paragraph' that tries to explain that figure differently.
In any case, the full ledger has a lot more clarity.
(Oh, in your highlights document - on page three - there's a 'Health Spending by Major Sources of Funds' - but I note that it's Health Spending they're describing there.)
That 30% is a source of funds. It’s the top of the second paragraph.