I am not sure where your number is coming from. The total amount of grain available on the world market last year was 157m tons. Russia plus Ukraine equals 55m of those tons. About one third of the global wheat supply.

Now the total amount grown is much higher. However, almost all of that is consumed internally by the countries it is produced in. It never goes on the market.

Case in point, India's recent restrictions on grain exports. Al Jazeera reported that the government suddenly panicked. When it realized that the harvest is going to be bad and that it had not purchased enough wheat to meet it's basic support for the poor.

It purchased 44m tons last year, all from internal sources. This year it had only purchased 18m tons and when it realized farmers were selling on the world market it halted exports.

Good for India bad for people who don't have another source of wheat.