Gartner forecasts that 3D printer unit shipments will grow at a CAGR of 121.3% through 2019, and that corresponding annual average spending will grow at 72.8% for the same period.  Additionally, Gartner expects that sales will exceed $14.6 billion in 2019 as consumers, educational institutions and businesses ramp up their purchases.

https://www.gartner.com/doc/3132417?ref=SiteSearch&sthkw=3d%20printers&fnl=search&srcId=1-3478922254