They are based on quarterly data submitted by local authorities to WasteDataFlow.
In this statistics release comparisons are made between the financial year April 2009 to March 2010 and the year October 2009 to September 2010, to minimise the effects of seasonal fluctuations.
The proportion of household waste sent for recycling, composting or reuse between October 2009 and September 2010 in England was 40.3 per cent, continuing the long term increase. The tonnage of local authority collected waste being sent to landfill was 45.0%, continuing the decrease since 2002/03.
Please see the release here: http://www.defra.gov.uk/statistics/environment/waste/wrfg22-wrmswqtr/.