Forex What is retail trading as % of total FX volume?

hi, i'm a little bit lost after reading some studies about retail traders and what they represent compare to the global fx market.

here, page 2 i can see that retails represent 20% of the spot volume
https://www.ecb.europa.eu/paym/group...bebe1c60d92ce4

here, results for 2010 are quite different from those of first link

https://www.ecb.europa.eu/paym/group...fe745feb1ad7f5


and here, in the rapport of BIS, page 39, it's written
"New breakdowns collected in the 2013 Triennial show that retail trading accounted for 3.5% and 3.8% of total and spot turnover, respectively "

http://www.bis.org/publ/qtrpdf/r_qt1312e.pdf

could someone explain to me what i don't understand ?? My english is not really good, so it doesn't help ,

retail are 3,10,20%,etc of spot volume ??

hope you'll can help me,

thomas

Source.