Perhaps a comparison with the LDS church would provide some clues:
http://www.xmission.com/~country/reason/lhm1097b.htm
TIME LOOKS AT MORMONS
By Jerald & Sandra Tanner
(This article originally appeared in The Salt Lake City Messenger, Issue No. 93, November, 1997)
Time magazine devoted 10 pages to an examination of the Mormon Church. The outside cover of the magazine shows a beautiful picture of the Salt Lake City Temple and carries this intriguing headline: MORMONS, INC. The Secrets of America's Most Prosperous Religion.
Time were very hard to obtain in Salt Lake City. Some Mormons who were fortunate enough to find copies were distressed with some of the observations found in the magazine. On the other hand, however, many Mormons were happy that the church received so much publicity.
Time:
Time has been able to quantify the church's extraordinary financial vibrancy. Its current assets total a minimum of $30 billion. If it were a corporation, its estimated $5.9 billion in annual gross income would place it midway through the FORTUNE 500, a little below Union Carbide and the Paine Webber Group but bigger than Nike and the Gap.
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By way of comparison: If every regular publisher since 1965 has contributed $25 per month (directly or through literature placements), the gross proceeds would amount to approx $32 billion.
Craig