Google's Knowledge Graph tripled in size in seven months | Internet & Media - CNET News

Not a bad start, compared to, e.g., Wolfram Alpha's "10+ trillion pieces of data"

"At launch, the Knowledge Graph was a database of the relationships among 500 million objects, and contained 3.5 billion facts. Less than seven months later, the graph covers 570 million entities and 18 billion facts -- as well as three times as many queries as it did when it started.
Whenever the Knowledge Graph recognizes a query it understands, the results show up in a box on the right-hand side of the page. The fact boxes resemble Wikipedia entries, and draw from a variety of publicly available and licensed data sources."

Google's Knowledge Graph tripled in size in seven months | Internet & Media - CNET News