Data from ASADA annual reports, as best as I was able to determine when I looked at it earlier this year:
In Australia it is normal for annual reports to use a July-June financial year reporting period rather than calendar years.
Note that this was as of March 2011 when I went through the reports. I haven't checked to see the current numbers for 2011.
If the latest report (2010/11) shows 42 doping violations in a 12 month period, then that is a significant increase (up 54%) on the historical average of 27 doping violations per year for last six years.
It would interesting to see if that is as a result of an increased in the number of tests, or better targeted testing. I doubt that, on average, athlete behaviour wrt doping has worsened to that extent compared to previous years.
edit - I just noted 7040 tests according to the article, so that means the 2010/11 doping violation rate went up to 0.6% of all tests.