Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
What was the 2006 population for the local government area of alexandrina council whose rank was smaller than 19?

### Inputs:
table_name: table, columns: ['Rank', 'Local government area', 'Population 2006 census', 'Population 2007 estimate', 'Growth rate', 'Stat. division/district']

### Response:
SELECT AVG Population 2006 census FROM table WHERE Local government area = alexandrina council AND Rank < 19