Refer to this link where JWD did a survey a week ago
http://www.jehovahs-witness.com/12/150611/1.ashx
I added all the partakers and congregations separately and arrived at
Partakers: 31
Congos: 62
Exactly half of the congos had partakers!. Using a conservative 90,000 congos gives 45,000 partakers world wide!