If a nation's annual real GDP growth rate is 2.5% we can expect real GDP to double in about _______ years.

Enter your answer rounded to one decimal place: For example: 49.450 would round up to 49.5; 49.449 would round down to 49.4. If the answer is a whole number you still must report it using one decimal. For example, 49.0 (not 49). This question is machine graded so it's important you report the answer as instructed.