is the US sailplane fleet shrinking?

I have found a very interesting article by Paul Schweizer in the
September 1990 issue of Soaring, titled "Is the U.S. Sailplane Fleet
Shrinking?" In it, the author discussed his fear that the answer is
Yes. He based this on a survey of the number of sailplanes that were
imported, and another survey of the number of classified ads for
sailplanes published in Soaring. In the first case, the number of
sailplanes imported had dropped precipitously from more than 140 in
1984 to less than twenty in 1989. The number of ads had also dropped
form a high of about 2000 in 1986 to less than 1000 in 1989.

According to the author, in 1989, there were 20 sailplanes exported
(with zero domestic production), 14 were lost to attrition, and 15 were
imported, for a net loss to the fleet of 19 aircraft. He cautioned that
accurate figures were not available for homebuilts, but he doubted that
the number of completed projects was even close to enough to make up
that number.

The article was written in 1990. Does anyone have more recent
information about this?

Johan Larson