You're looking at the Yahoo page and one should never ever trust what they write. They don't even have the last two dividends in the historical prices when you click on that option. So ignore what they say.
In 2010 PETDX paid a total $1.725 distribution and started the year with an NAV of $4.47. So that was a yield of 38.59% for 2010.
The dividend changes from quarter to quarter depending on the NAV performance. Rather than let the NAV climb PETDX pays out the NAV increase in a dividend, for the most part. It's why it has an average annual dividend yield of 22.9758% over the past seven years. It is a cash dividend machine. The catch is that if it has a bad year and the NAV declines as it did in 2008 then there was no dividend at all in either 2008 or 2009. So that 22.9758% yield over seven years includes two years with no dividend at all. The annual dividends ranged from 0% to 41.48%.
So that's the long answer to your question :-) Although I could go on.... if you would like. I think it's a great fund for a Roth or regular IRA for income. If you can tolerate the erratic payout.