UnConfused, here is some information that might interest you regarding the number of Memorial partakers.
1) Number of Memorial Partakers since 2000. Shows a definite increase.
2000 - 8661, 2001 - 8730, 2002 - 8760, 2003 - 8565, 2004 - 8570, 2005 - 8524, 2006 - 8758, 2007 - 9105, 2008 - 9986, 2009 - 10857, 2010 - 11202, 2011 - 11824.
2) Watchtower tries to explain away the unexpected increase by saying some of them may be 'emotionally imbalanced.'
(W 8-15-11 p22)
"Memorial partakers. This is the number of baptized individuals who partake of the emblems at the Memorial worldwide. Does this total represent the number of anointed ones on earth? Not necessarily. A number of factors - including past religious beliefs or even mental or emotional imbalance - might cause some to assume mistakenly that they have the heavenly calling. We thus have no way of knowing the exact number of anointed ones on earth; nor do we need to know. The Governing Body does not keep a list of all partakers, for it does not maintain a global network of anointed ones."
3) This new trend contradicts the Watchtower teaching from the past that the declining number of partakers was proof that we are in the last days.
(W 1-15-2000 p13)
“Six convincing lines of evidence that we are in the last days”… "Sixth, the number of genuine anointed disciples of Christ is dwindling, though some will evidently still be on earth when the great tribulation begins. Most of the remnant are quite elderly, and over the years the number of those who are truly anointed has been getting smaller.”
- and -
(1981 Yearbook, p31)
Over the past seven years, from 1974 to 1980 inclusive, Jehovah’s Witnesses have made steady progress. Their growth is healthy. Only as to Memorial partakers has there been a gradual decline, which is in accord with Scriptural expectations.
As to the date of their sealing, I believe it was 1935, but I don't have that info in front of me. Someone can correct that if it's wrong.
I'm looking for the latest reference that changes the 1935 sealing to an undetermined date. Can't find it for now. Will keep looking, but someone may beat me to it.