The proposed acquisition of the CHX by the Casin group. The Chinese group looking to acquire the CHX. That's why it only covers Asia. Active trader-defined as we would a day trader. The CFIUS data.
The NASAA should have an estimate for the US. The only one they have up now is from their 1999 study and no longer relevant.
There is data all over the internet - I would consider the sources. Here is an academic study from Taiwan that seems to place it about 7 - 9000 in 2004. So kind of dated and the definition of active is open to debate.