Well, I donlt think it is so clear cut,

have a look this map on the tagesschau site
http://stat.tagesschau.de/wahlarchiv/wid246/index.shtml

it shows there are more black areas - overall, CDU/ CSU have also more first votes than the SPD,
It also means that theoretically more Laender should be run by Social Democratic governments, like infuriatingly NRW, which they are not.

Well, that might change again...