IFI

Patent Intelligence & Technology Report

Class Distribution for 1990-1999 

175 - BORING OR PENETRATING THE EARTH (IPC E21B)

       1999  1998  1997  1996  1995  1994  1993  1992  1991  1990  Total

DRESSER INDUSTRIES INC
          6    12     5     7     8     2     3     2     7     1     53
ATLANTIC RICHFIELD CO
          1     1     0     0     3     3     5     4     1     2     20
GAS RESEARCH INSTITUTE
          0     1     1     0     0     0     0     0     0     4      6
NATIONAL RESEARCH COUNCIL OF CANADA CA
          0     0     1     0     0     0     0     0     0     0      1

Total     7    14     7     7    11     5     8     6     8     7     80