user: Question: What is the total number of regions where the average family size is 2.8?
Columns: ['Region of USSR', 'Number of families', 'Number of people', 'Average family size', '% of total deportees']
Types: ['text', 'real', 'real', 'text', 'text']
Sample row: ['Amur Oblast', 2028.0, 5451.0, '2.7', '5.8']
SQL:

assistant: SELECT COUNT("% of total deportees") FROM "Table" WHERE "Average family size" = '2.8';