Ann: OHD Crop Trials, page-242

As of the first of January 2016, the acreage devoted to greenhouse vegetable growing globally is estimated at 473,466 hectares

Australia fourth in world for greenhouse vegie growers

Targeted for a 60-acre site, AppHarvest’s 2 million square-foot greenhouse will rank among the world’s largest.
February 23, 2017
https://businessfacilities.com/2017/02/high-tech-greenhouse-creating-140-jobs-in-kentucky/
Iran to transfer all veg farms to greenhouses
Greenhouses cover 11,400 hectares in Iran
5/2/2017
http://www.hortibiz.com/item/news/iran-to-transfer-all-veg-farms-to-greenhouses/
This is the future of farming
http://www.theaustralian.com.au/lif...g/news-story/99fd0a207d8b6aa0768c32fd61b3d00e
Greenhouse vegetable acreage up 14% globally in 2015
28th Jan 2016
http://www.aginnovators.org.au/news/greenhouse-vegetable-acreage-14-globally-2015
Vertical farming yields more crops per square metre than traditional farming or greenhouses do. Vertical farming also uses less water, grows plants faster, and can be used year-round – not just in certain seasons. The facilities also can, in theory, be built anywhere.
http://www.bbc.com/future/story/20170405-how-vertical-farming-reinvents-agriculture

GPP's timing on Hydroponics is quite interesting