user: Question: How many polls taken on different dates show an undecided percentage of 25%?
Columns: ['Date of opinion poll', 'Conductor', 'Sample size', 'For', 'Against', 'Undecided']
Types: ['text', 'text', 'real', 'text', 'text', 'text']
Sample row: ['27 September 2009', 'Sunday Independent/Quantum Research', 1000.0, '68%', '17%', '15%']
SQL:

assistant: SELECT COUNT("Date of opinion poll") FROM "Table" WHERE "Undecided" = '25%';