By Martin Aston
- View notes at gyford.com.
- View official site at martinaston.co.uk.
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- No data available for before 1980, 1982–1985, 1987–1989.
- Data is incomplete for 1980, 1981, 1986, 1990, 1991 and 1997.
- Specific dates (rather than just a year) only recorded in the 1980s and since 2005.
- Reading of periodicals only recorded since 2005.