Sales and marketing expenses increased by $930 million, or 58%, from 2016 to 2017. This increase was primarily due to $419 million in higher advertising and other marketing programs spend, $331 million in increased consumer discounts, promotions, refunds, and credits.
Sales and marketing expenses increased by $627 million, or 25%, from 2017 to 2018. This increase was primarily due to increased consumer discounts, promotions, refunds, and credits.