http://u.qdnx.org/file/rozzin-20181120T103241-r5ng7e9.html
A comparative chart of caffeine-densities of 9 brands of !coffee, with McDonald's on the low end at 9.1 mg/floz and Death Wish at the high end with 54.2 mg/floz: https://www.huffpost.com/entry/caffeine-in-coffee_b_3671665