They are based on quarterly data submitted by local authorities to WasteDataFlow.
In this statistics release comparisons are made between the financial years April 2010 to March 2011 and the rolling year July 2010 to June 2011, to minimise the effects of seasonal fluctuations.
The proportion of household waste sent for recycling, composting or reuse between July 2010 to June 2011 in England was 42.0 per cent, increasing from 41.5 per cent in the financial year April 2010 and March 2011.
The generation of household waste continued to decrease between the financial year 2010/11 and the rolling year July 2010 to June 2011, with a 0.9 per cent reduction to 23.2 million tonnes. This continues the slowing in a reduction of household waste since 2007/08.
The full release can be found here