27%: Of the top 40 songs are collaborations.

This image appears in the gallery:
This Week's Chart By Numbers (8th March 2015)

1. 
2. 
3. 
4. 
5. 
6. 
7. 
8. 
9. 

10. 11 images

See the full gallery: This Week's Chart By Numbers (8th March 2015)