*I'm not exactly sure what it means by compare the percents of change*
From 2000 to 2005, that's 5 years.
After 5 years, the population decreased from 4.3 mil to 3.2 mil; 3.2 - 4.3 = -1.1; that's a decrease of 1.1 mil.
1.1 mil out of 4.3 mil is approximately 26%.
So from 2000 to 2005, the population decreased by 26%.
From 2005 to 2010, that's also 5 years.
After that 5 years, the population increased from 3.2 mil to 5.6 mil; 5.6 - 3.2 = 2.4; that's an increase of 2.4 mil. 2.4 mil out of 3.2 is 75%.
So from 2005 to 2010, the population increased by 75%.