The sweater features Santa with looks to be three lines of cocaine.
This increase was driven mainly by people aged 18 to 24, for whom usage almost tripled.
Some sites are completely free and depend on advertising for revenue.
Others utilize the freemium revenue model, offering free registration and use, with optional, paid, premium services.
At the same time, usage among those between the ages of 55 and 64 doubled.
People in their mid-30s to mid-50s all saw noticeable increases in usage, but people aged 25 to 34 saw no change.