there is some interesting statistic available from this German site.
http://www.gas-tankstellen.de/menu.php?jump=verteilung
it has an english language selection on the top right - but seems to have no impact on that particular page though.
http://www.gas-tankstellen.de/menu.php?jump=verteilung
it has an english language selection on the top right - but seems to have no impact on that particular page though.