"estimated" being the key word!
Not sure if this is too far off topic... but here are the interesting facts that may shed some light who was first where...
Remember Corded Ware Culture? it's 3200 - 1800 BCE...atributed to R1a...
see
eupedia.com/europe/neolithic_europe_map.shtml
(sorry I needed to remove h-t-t-p:// and w-w-w from links below... guest rules)
here comes something really interesting..."the earliest family reported" - see Eulau ... tests show R1a...
dienekes.blogspot.com/2008/11/y-chromosomes-and-mtdna-from-eulau.html
It confirms the presense of R1a in the central of Germany at 2600 BCE ... this really must be embarassing to some Germans...
And here is another one...
en.wikipedia.org/wiki/Lichtenstein_Cave
Among others there were two R1a and one R1b...
To me it sounds like 4:1 for R1a ... at least in that area.
One may say - well it's the fact R1a was there because it was the part of Corded Ware expansion! So what's the big deal? But I thing it is a big deal cause those ARE the eldest artifacts that come from the "hard core" German theritory and they clearly point to R1a (proto Slavic?) genome. Not too many R1b's reported from that time... and it had been a couple of thousands years while they were there...