Nice job Hans! I like the representation IMHO. I was thinking it wold be useful to replace interregional (circles) with immigration to the Netherlands, and the lines as interregional (between regions). As for intraregional, that would be within each region, which is not shown. That would show people coming into the Netherlands and how people move within the country within 1 year.
Would be a great submission to a magazine or newspaper.
Actually, the sizes of the circles represent how many people have moved within that region.
One of the reasons why I plotted them like this (with the 2 axes) was so that it would be obvious which regions have a discrepancy in immi-/emigration, but it turns out they're all pretty much balanced in that respect.
I was also amazed at the fairly low numbers for migration between regions (you all notice I'm staying away from the long, difficult words now). South to North for example is merely 1800-something (makes sense, it's much cooler down here...)