These are Soviet population census figures for the top nationalities in the Soviet Union in 1926. The number of Russians rose by 21% in 11 years, showing a normal rate of growth, and the number of Ukrainians fell by 15%, showing a highly abnormal fall of population and resulting in the difference of 36% between Russians and Ukrainians, which corresponds to at least a 10 million decrease in the population of Ukraine within the same time period, assuming similar birth rates in Russia and Ukraine. In effect, in just 11 years the number of Russians vs. Ukrainians went from a ratio of 2:1 to a ratio of 3:1, which still holds today.
The only people who have suffered at least as heavily in the same time period are the Kazakhs, not so much from famine, but from forced resettlements and death marches of populations of entire areas of Kazakhstan. The Soviet state took the nomadic population of Kazakhs and forcibly resettled them into kolkozes. This should also qualify as genocide - of the Kazakhs. But in numerical terms, since the number of Ukrainians was so much greater than the number of Kazakhs, Ukrainians lost about 10 times as many people as the Kazakhs.
Additionally, the Soviet leadership, and Stalin in particular, were motivated to inflate the number of Ukrainians in the 1937 Soviet Census. It is a known fact that after they returned a number of Ukrainians that was too small for his liking, Stalin had the Census Director responsible for Ukraine executed, and ordered another Census in the territory of Ukraine, which came back with a higher number of Ukrainians.
My previous post on the topic:
http://ukraineblogg.blogspot.com/2008/09/remembering-holodomor-ukrainian.html