Keep in mind that this is "increase in height over the past 100 years" which does not translate to "current standard of living." If a country already had a fairly high standard of living, one would expect that simply throwing more calories/protein into the mix wouldn't do much -- the population could be nearing its "peak height" already. If you're a poor country whose standard of living hasn't improved much over the last 100 years, your "average height increase" may look identical to those countries in the first category, but for very different reasons.

In addition, like one of the commenters mentioned, the US has seen tremendous immigration from countries (Top countries that people immigrate to the US from: Mexico, India, China, The Philippines, Cuba) that, on average, have been shorter than European and West African populations, also contributing to the change in average height.

If you look at some of the other "rich countries" in the list, they're smack dab in the middle of some other surprising countries. Sweden is between Vanuatu and Botswana, and Germany's increase in height is identical to North Korea's, for instance.