If the Hang Seng index rose from a level of 21,914.40 on December 31, 2015 to 28,189.75 on December 31, 2019, what was the annualized return on the Hang Seng index over the period? Please enter your answer as a percentage rounded to two decimal places as follows: If your answer is 11.3897%, please enter 11.39 (without a percent sign)