The Canada numbers include teenagers (persons aged 12+) while the US ones do not (persons aged 18+).
Also, the Canada numbers went from 13% (lower than the reported US rate) in 2015 to 15.1% (higher than the US rate) in 2017. That 13 to 15.1% increase over two years seems to be a statistical anomaly as it goes sharply against the overall trend (according to your source):
"Despite the overall prevalence increase in the most recent survey year, from 1999 to 2017, the overall trend was an average annual decrease in prevalence of 3.2% of the previous year’s value"
TLDR; the average over the last several years is more or less the same.