At any given month wheat is being harvested somewhere in the world. Most of this production is consumed locally with purchases, by the country, required to meet the total food demand. To purchase this wheat they need to go to OWEC -- Organization of Wheat Exporting Countries: Canada, US, Brazil, & etc. As the wheat stocks available within OWEC for export diminishes the price rises and the countries purchasing the stocks cannot afford to buy what they need. So they buy less. But even that less removes stocks so the price rises and other countries have to pay more, for less, but they purchase .... and 'round and 'round we go.
To express this dynamic relationship the FAO chose to express the available wheat to no wheat as a ratio.
Why? No idea. They just did.
Luis de Souza posted a map showing exceptional climatic events (essentially higher-than-average temperatures), which correlated to areas producing less wheat than usual this year (Canada, Australia, Ukraine). Unfortunately it doesn't display any more (hotlinked from NASA, has disappeared since posting). Pity.
My point is that, rather than say Peak Wheat, we should be looking at climate disturbance due to GW for a major cause of the recent fall in yields.
