Population Question

Chicago population went from 2,701,705 in 1920 to its max of 3,620,962 in 1950 then it started to decline after that from 1980 t0 1990 chicago's population went from 3,005,072 to 2,783,726. So 1980 was the last time that we saw 3 mil. That was 26 years ago. Now that the city's population is back on the upswing, how long until we see 3mil again? The city's population jumped by almost a million between that 30 year stretch from 1920 to 1950, How long until we see 3.6mil again. Will the olympics serve as a catylst to both development and population?>