statement 12 months. IO need to ensure 400k in account at all times for last 1 year, and 800k for 2 months before your renewal, and 800k for 3 months after your last renewal.
Coming here and asking will most likely give you another 8+ different seperate answers. Is there a particular answer you are hoping to see here, which would fully satisfy your queries?
As per previous advice, head down to Immigration and ask them... they do not bite!