* The source indicates: "The source of this information is the Opinions and Lifestyle Survey (OLS). The OLS is a multi-purpose survey developed by ONS for use by government departments, other public bodies, charities, academics and the media. It provides a fast, cost effective and reliable way of obtaining information on topics too brief to warrant their own survey."

** The Opinions and Lifestyle Survey is carried out by interviewing a nationally representative sample of households in Great Britain. About 1,800 households are sampled each month and estimates are subject to sampling variability, as are those from all sample surveys.