I think the chart is probably correct too. Argentina's economy basically came to a stand-still so the amount of debt as a percentage of GDP will have increased dramatically in a very short time due to the sudden fall in GDP.
It also must be remembered that at the time one of the big problems was that the arg peso was pegged to the us$, and while other countries currencies were dropping against the us$ the arg peso wasnt, so arg exports became very expensive for their biggest trading partner - brazil, and brazilian imports to arg became very cheap, so exports decreased, imports increased, and local manufacturers couldnt compete. This all happened in a very sort time frame.
I would say a better way to look at this is that debt has been decreasing since 2004 (due to being written off mostly and some repayments), but GDP dropped dramatically in 2004, then has increased thanks to an export lead recovery due to the currency devaluing, commodities prices increased etc..