The Dynamic Duo is a value$-$weighted index with two stocks: A and B$.$ A constituted $75\%$ of the value of the index at the beginning of the year. During the year, A went up $15\%$ and $B$ rose $6\%.$ What was the percentage change in Dynamic Duo index over the year?

Enter your answer as a percentage rounded to one decimal place.

Percentage change $=|13\mathrm{.}4\%||$