That graph is not even accurate.
This says Canada's health care spending is $6600 per person: https://www.ctvnews.ca/health/canada-to-spend-more-than-6-60... while your graph says its $4500. Those numbers aren't even in the same ballpark.
Find any source - any reputable source - that indicate US healthcare costs are anywhere near the rest of the OECD.
My actual findings (2017): United States: $9250 Canada: $6600 Ratio: 1.40
I think your graph is fake news.
Sources: https://www.npr.org/sections/goatsandsoda/2017/04/20/5247741... https://www.ctvnews.ca/health/canada-to-spend-more-than-6-60...
The NPR link you cite has Canada at 4576 and the US at 9237, for a ratio of 2.02. The CTV link (citing a different organization; perhaps one considers dental/eyeware and the other doesn't, or something along those lines) doesn't offer US numbers to compare against.
Wikipedia has a consistently-sourced list you can peruse, too, for multiple years: https://en.wikipedia.org/wiki/List_of_countries_by_total_hea...