Is it D? Reasoning as below:
Lets assume that 10 yrs back out of 100 people 50 retired and settled in Florida....so Florida % was 50%
Now acc to D, no of people who retire and settle somewhere else has increased. Lets assume 150 people. Then out of 150 if 70 retire in Florida, the % decreases to 46.6 while the no of people still increases.