In 2006, there were only about 200 known cases worldwide.

It is the only known case of retaliation so far.

There were no known cases in which health workers had become infected through blood.

There are few known cases of that having happened in this country.

There were 10 known cases in 1989, compared with an average of more than 50 a year from 1975 to 1983.

He also claimed it was the first known case of its kind in the country.

New York's first two known cases, in 1979, were his sexual partners.

It is a very rare condition with about 30 known cases in 2002.

Approximately 200 known cases have been reported in the literature.

This is the only known case of a human being hit by a rock from space.