[VOIPSEC] What % of voip apps or devices actually use SRTP or ZRTP to encrypt audio calls

[SM]

Hi,

  I was wondering about what percentage of voip apps or devices actually use
SRTP or ZRTP to encrypt audio calls in 2010. Are there any confirmed
statistics for this? Has any study been done on this? Can I and where can I
get such data?

  Thanks for your early reply and have a wonderful day ahead.

Regards,
 SM.