From: Circumstantial evidence for an increase in the total number and activity of borrelia-infected ixodes ricinus in the Netherlands
Density
2000
2004
2008
Change 2000-2008
High
   4399 km2
   4483 km2
   5246 km2
19%
Low
15608 km2
15517 km2
15645 km2
1%
Zero
13744 km2
13755 km2
12652 km2
−8%