Ahead of the G8 summit, Forsa polled a thousand Germans on whether they knew the eight heads of government, and asked them to rate them from 100 (best) to 0 (worst).
i didn't see the data on how many Germans knew about Shinzo Abe or Stephen Harper - might be interesting as well - but here's the average ratings:
Merkel 62
Prodi 51 (only one that would've gotten a higher rating from me, tho' not much higher)
Sarkozy 49
Blair 47
Harper 44
Abe 41 I think, doing this from memory. Between Harper and Putin, anyways
Putin 39
Bush 20