This image shows the lowest value of ozone measured by TOMS each
year in the ozone hole.  Global average ozone is about 300 Dobson
Units.  Before 1980 ozone less than 200 Dobson Units was rarely
seen.  In recent years ozone near 100 Dobson Units has become
normal in the ozone hole.  Ozone in the year 2002 ozone hole was
higher than we have come to expect because of unusually high
temperatures in the Antarctic stratosphere.