In 2004, an estimated 81 million hectares of GM crops were planted worldwide. This corresponds to about two and a half times the land area of the British Isles. Annually, there has been a double-digit percentage increase in the worldwide GM crop growing area since 1996. From 2003 to 2004. the increase was around 20%.
It is not really possible to estimate the percentage of GM in the national diet. There are not many GM whole foods yet available, even in the US and Canada: tomatoes, sweetcorn and papayas are the main examples.
In North America, 70% of processed foods are estimated to contain GM ingredients. For the UK the answer is less clear. Many British supermarket chains say their own house brands are free from GM components but whether this means "totally free" or "substantially free" is not obvious. Supermarket non-house brands normally do not make such a claim. Even "organic foods", which aim to be totally free from any transgenic material, have been found to contain measureable quantities.
The major crops that have been genetically modified to date include soybean, maize, cotton, potato, squash, papaya and oilseed rape. Work is ongoing on many other plant types.
ISAAA Briefs 32-2004: Preview: Global Status of Commercialized Biotech/GM Crops: 2004 (http://www.isaaa.org)
Mark Partridge and Denis J Murphy (2004). Detection of genetically modified soya in a range of organic and health food products: Implications for the accurate labelling of foodstuffs derived from potential GM crops. British Food Journal, 106, 166-180 (http://lysander.emeraldinsight.com/vl=2375658/cl=27/nw=1/rpsv/cgi-bin/cgi?ini=xref&body=linker&reqdo