Here you can find the total column ozone amount over any point on Earth for most dates between November 1978 and December 1994 and from August 1996 to today. Just click on the map.
Note: This is not the amount of ozone that causes smog (tropospheric ozone), but rather a measure of ozone density through an entire column of atmosphere, from ground to space. This measurement is dominated by high altitude ozone (stratospheric ozone). See the Dobson unit entry in Wikipedia for more detail.