This result is from a 2014 paper by Damon Matthews et al, "National contributions to observed global warming." The US is by far the biggest absolute contributor -- and even up through 2012, the US had emitted 2.4 times more than the Chinese and 9.6 times more than India.
(I used data from another source to estimate these numbers up to 2014, and got 2.1 times more than China and 8.6 times more than India.)
So it's rather ridiculous to complain about China and India when we've already contributed more than both combined.
But per capita, it's actually Great Britain that leads all other countries. All that coal burning in Dickensian London, I suppose. This is from the paper cited above (remember, it's only 1850-2005):
So Canada doesn't look so good, either, per capita. India practically vanishes.
Here's another graphic from that paper, again showing who leads in per capita emissions and who hasn't (yet) become affluent by emitting them: