How many background track types are available for Streaming synthetic voices?

The following 38 background tracks are currently available:

1. (Classical) Lucky Pets
2. (Classical) Figure It Out
3. (Classical) Pizzi Caper
4. (Classical) Creating A Masterpiece
5. (Club/Electronica) Give Up The Night
6. (Club/Electronica) Light Parade
7. (Country) City Girl Country Boy
8. (Country) Keep Thinking Keep Drinking
9. (Country) Soak Up The Sunshine
10. (Country) Twang Time
11. (Dance) Shine
12. (Folk) Sunshine In Spring
13. (Folk) Cushion boogie
14. (Hip Hop) Booty Booming
15. (Hip Hop) Barbaric Splendor
16. (Hip Hop) Massive Mama Jama
17. (Hip Hop) Crowd Pleaser
18. (Indie) Snappy And Happy
19. (Indie) Blueprint Design
20. (Jazz) One More Time
21. (Jazz) Walking in Birdland
22. (Jazz) Diggy Diggy Do
23. (Latin) In the Calle
24. (Latin) Con Tumbao
25. (Latin) Como Animales
26. (Percussion) Bucket Boys
27. (Percussion) Technicolor Dreams
28. (Pop) Endless Summer
29. (Pop) Festive Youth
30. (Pop) Fun Starts Here
31. (Pop) Plug and Play
32. (Pop) Sandbox
33. (Pop) Lets all Go Together
34. (R&B) Gotta Have It
35. (Rock) More Cowbell
36. (Rock) Fresh Find
37. (Rock) Blood Money
38. (World) An Odd Bird