What's different about Botswana?

Scott Beaulier draws a rather neat graph. ("SSA" is Sub-Saharan Africa.) The country has had GDP growth of 5.3% and 3.3% the last two years. A question we want to answer in class is, why? What's different about Botswana? Is there any way to generalize it? Beaulier points out that it's using lots of deficit spending. He calls it bad news. Why?