BEGIN EDIT: I think I misread the Britannica part. Netherlands has half of it’s area highly developed and half of that highly developed area is low lying, so a quarter of the total. END EDIT
The Netherlands is an example of a country highly susceptible to both sea-level rise and river flooding because 55% of its territory is below sea level where 60% of its population lives and 65% of its Gross National Product (GNP) is produced
If this too is wrong, you bet the WG1 people are pissed off. (WG1 is the scientific basis, WG2 the effects and WG3 is the mitigation ways working group of IPCC.)
But it seems Britannica has information in similar vein:
The Netherlands is bounded by the North Sea to the north and west, Germany to the east, and Belgium to the south. If the Netherlands were to lose the protection of its dunes and dikes, the most densely populated part of the country would be inundated (largely by the sea but also in part by the rivers). This highly developed part of the Netherlands, which generally does not lie higher than about three feet (one metre) above sea level, covers more than half the total area of the country. About half of this area (more than one-fourth of the total area of the country) actually lies below sea level.
So, the question becomes tides and how sea level is measured: if it’s the mean sea level, then even low stuff over sea level is unlivable because of the tides (unless you put dikes and pump it dry of course).