US GDP is ~19 Trillion. If US Health care spending is 18% of GDP, that's about 3.5 Trillion annually. Pfizer's (largest drug co) net income in 2017 was ~21 Billion [0], less than one percent of health care spending. I didn't tally the rest of the industry up, but I'd be surprised if it hit 10% of total costs.
Actually, both revenue and income are proxies for the relevant number, given that I had in mind to address the GP's point of 'effectively funding a significant portion of R&D.' If the article [0] is to be believed, that's about 8-9 Billion for Pfizer, and about 70 Billion for the top 15 pharma companies, about 2% of US health care spending. Even if we cut US health care spending in half (to, say, the UK's level), funding pharma research at current levels would be a fraction of total costs.
[0] https://en.wikipedia.org/wiki/Pfizer