Value of products sold by Amazon in all markets. This doesn't include marketplace sales, which can be expected to be 1.5-2x of net sales value.
Last reported quarter 2017 Q3 it was $28.77 billion, up by 29% from $22.34 billion the same quarter a year before.
Since 2015 it increased by 19%, from $79.27 billion to $94.67 billion in 2016.
Source: Amazon Quarterly Results.