During the years 1978-1987 the hole grew, both in depth (total ozone loss in a column) and in area. This growth was not monotonic but seemed to oscillate with a two-year period (perhaps connected with the "quasibiennial oscillation" of the stratospheric winds.) The hole shrank dramatically in 1988 but in 1989-1991 was as large as in 1987, and in 1992-95 was larger still. In 1987 and 1989-95 it covered  the entire Antarctic continent and part of the surrounding ocean. The exact size is determined primarily by meteorological conditions, such as the strength of the polar vortex in any given year. The boundary is fairly steep, with decreases of 100-150 DU taking place in 10 degrees of latitude, but fluctuates from day to day. On occasion, the nominal boundary of the hole has passed over the tip of S. America, (55 degrees S. Latitude). Australia and New Zealand are far outside the hole, although they do experience ozone depletion, more than is seen at comparable latitudes in the Northern hemisphere.  After the 1987 hole broke up, December ozone levels over Australia and New Zealand were 10% below normal.