According to data from the 1976 and 1998 issues of the International Zoo Yearbook:
* In 1975 Basle Zoo, Switzerland, had 3 proboscis monkeys. In 1997 it reported none.
* In 1975, Berlin Zoo, Germany, reported 6 proboscis. In 1997 it reported none.
* In 1975 Cologne Zoo, Germany, reported 2 proboscis. In 1997 it reported none.
* In 1975 Colorado, USA, reported 1 proboscis. In 1997 it reported none.
* In 1975 Dallas Zoo, USA, reported 5 proboscis. In 1997 it reported none.
* In 1975 Frankfurt Zoo, Germany, reported 2 proboscis. In 1997 it reported none.
* In 1975 Milwaukee, USA, reported 2 proboscis. In 1997 it reported none.
* In 1975 San Diego Zoo, USA, reported 3 proboscis. In 1997 it reported none.
* In 1975 Stuttgart Zoo, Germany, reported 4 proboscis. In 1997 it reported none.
* In 1997 Twycross Zoo, England, reported 4 proboscis. In 1997, it reported none.
* In 1975 the Bronx Zoo, USA, reported 8 proboscis, seven of them born at the zoo. Sadly, most are now dead.
From the website
Dutch monkeys
(accurate or not, who knows?)