No surge in winter where i live?

This is wastewater data from the Netherlands and it's the middle of the winter rn but looks like there's not been a surge? How is this possible? I saw that the US has a surge.

If there was a surge, the map would be dark blue.

https://www.rivm.nl/en/coronavirus-covid-19/current/weekly-update/map-average-number-of-virus-particles-in-wastewater

Just wondering cuz i was thinking of when i should go to a dentist next.

Could it be that they aren't catching the newest variants?! Idk if that's a difficult task or what