As a reader noted, this chart is essentially unreadable. It contains data for the composition of diets in four countries during two time periods.
What might we want to learn from this data?
Are there major differences in diet between countries?
Within each country, are there changes in diet composition over the thirty years?
If there were changes in diet inside a country over time, did those reflect a worldwide trend or a trend specific to that country?
Unfortunately, the use of donut charts, albeit in small multiples, does not help the cause. The added dimension of the size of the pies, used to display the total calories per person per day, serves little purpose. Seriously, who out there is comparing the pie sizes rather than reading off the numbers in the donut holes if she wants to compare total calories?
This data set has much potential, and allows me to show, yet again, why I love "bumps charts".
Here is one take on it. (Note that the closest data I found was for six different countries - China, Egypt, Mexico, South Africa, Philippines, India - and for different periods.)
The set of small multiples recognizes that the comparison between 1970 and 2000 is paramount to the exercise. There is a wealth of trends that can be pulled out of these charts. For example, the Chinese and Egyptians take in much more vegetables than the people of the other countries; in particular, the Chinese increased the consumption of vegetables drastically in those 30 years. (top row, second from left)
Or perhaps, for sugars and sweetners, consumption has increased everywhere except for South Africa. In addition, the Chinese eat a lot less sugars than the other peoples. (top row, right)
Egg consumption also shows an interesting pattern. In 1970, the countries had similar levels but by 2000, Mexicans and the Chinese have outpaced the other countries. (bottom row, right)
These charts are very versatile. The example shown above is not yet ready for publication. The designer must now decide what are the key messages, and then can use color judiciously to draw the reader's attention to the relevant parts.
Also, some may not like the default scaling of the vertical axes. That can be easily fixed.
Finally, here is another take which focuses on countries rather than food groups. We note that too many categories of foods make it hard to separate them.
References: "Who's Eating What?", Wired, Oct 2008; "The Double burden of malnutrition", FAO, 2006.