Spending during the years Reagan budgeted (FY 1982–89) averaged 21.6% GDP, roughly tied with President Obama for the highest among any recent President. Each faced a severe recession early in their administration. In addition, the public debt rose from 26% GDP in 1980 to 41% GDP by 1988. In dollar terms, the public debt rose from $712 billion in 1980 to $2.052 trillion in 1988, a roughly three-fold increase.  The unemployment rate rose from 7% in 1980 to 11% in 1982, then declined to 5% in 1988. The inflation rate declined from 10% in 1980 to 4% in 1988.
Question: How many percentage points of GDP did the public debt rise between 1980 and 1988?
Answer: 15