Table:
text: List of places in South Australia by population
25 largest local government areas by population
25 largest local government areas by population
Rank_ Local_government_area Population_2006_census Population_2007_estimate Growth_rate Stat_division_district
12. Adelaide Hills Council 39601 39691 0.2% Adelaide
13. City of Unley 37826 38104 0.7% Adelaide
14. City of Norwood Payneham & St Peters 35255 35571 0.9% Adelaide
15. City of Holdfast Bay 34704 35037 1.0% Adelaide
16. District Council of Mount Barker 27612 28270 2.4% Adelaide
17. City of Mount Gambier 24494 24640 0.6% Mount Gambier
18. City of Whyalla 22332 22612 1.3% Whyalla
19. Alexandrina Council 21505 22026 2.4% Alexandrina
20. Barossa Council 21407 21806 1.9% Barossa
21. City of Prospect 20063 20354 1.5% Adelaide
22. Town of Gawler 19406 19841 2.2% Gawler
23. Rural City of Murray Bridge 18364 18595 1.3% Murray Bridge

Question: From the list of places in South Australia, what was the population in 2006 for the local government area of Alexandrina Council whose rank was less than 19?