The bar graph given alongside shows the number of visitors visited a historical place from March to July. Read the bar graph and answer the following question: What is the percentage change in the number of visitors in the last two months from first three months?
The ages(in years) of the visitors to a shop are as follows: 13, 18, 13, 14, 13, 16, 14, 21, 13. The average age of the visitor is ______.