Brandwatch collected and analyzed every emoji published on Twitter over the course of two years. It amounted to 6,400,278,100 emojis. On average we use 7-9 million emojis every day, which equals 250 million emojis posted online each month.
You may be interested in the analytics behind the reporting.
You may be interested in knowing the most used top 20 emojis (and more insights).