For Q1 2022, pharmaceutical sales only...
AbbVie: 10.345 Bn US vs. 3.19 Bn ex-US [0]
Roche: 5.292 Bn US vs. 5.308 Bn ex-US [1]
BMS: 7.694 Bn US vs. 3.954 Bn ex-US [2]
So US provides at least >= 50% of total revenue, and in some cases considerably more. Also, given the higher prices, it's likely that the US represents a considerably higher proportion of profit than this - and therefore a major change in drug pricing in the US would be hugely disruptive for the industry.
--
[0] https://investors.abbvie.com/static-files/b37af441-45e9-4e16...
[1] https://www.roche.com/cec228fd-2a55-41e7-a718-19e658c7048d
[2] https://news.bms.com/news/details/2022/Bristol-Myers-Squibb-...