Here is the yearly manga sales ranking for November 23rd 2009 - November 21st 2010.
*1, 2,593,580 One Piece vol.59
*2, 2,578,730 One Piece vol.57
*3, 2,557,356 One Piece vol.58
*4, 2,492,183 One Piece vol.60
*5, 2,480,124 One Piece vol.56
*6, 1,340,772 Fullmetal Alchemist vol.25
*7, 1,298,292 Fullmetal Alchemist vol.24
*8, 1,241,997 Nodame Cantabile vol.24
*9, 1,214,468 Fullmetal Alchemist vol.26
10, 1,211,849 Naruto vol.49
11, 1,200,432 Naruto vol.50
12, 1,194,176 Naruto vol.52
13, 1,148,107 Kimi ni Todoke vol.10
14, 1,145,107 Naruto vol.51
15, 1,134,992 Kimi ni Todoke vol.11
16, 1,083,258 Kimi ni Todoke vol.12
17, 1,030,345 Naruto vol.53
18, *,968,112 Nodame Cantabile vol.24
19, *,941,550 Hunter x Hunter vol.27
20, *,885,784 Saint Young Men vol.5
21, *,842,401 Neon Genesis Evangelion vol.12
22, *,822,401 Bleach vol.42
23, *,780,241 Bleach vol.44
24, *,769,697 Bleach vol.45
25, *,769,271 Bleach vol.46
26, *,760,433 Bleach vol.43
27, *,690,119 Bleach vol.47
28, *,664,200 Kuroshitsuji vol.8
29, *,619,211 Kuroshitsuji vol.9
30, *,604,235 Katekyo Hitman Reborn! vol.27
31, *,593,897 Katekyo Hitman Reborn! vol.28
32, *,591,220 Detective Conan vol.67
33, *,585,862 Thermae Romae vol.1
34, *,582,651 Katekyo Hitman Reborn! vol.29
35, *,577,093 D.Gray-man vol.19
36, *,574,888 One Piece Green Secret Pieces
37, *,567,217 REAL vol.9
38, *,565,657 Detective Conan vol.68
39, *,555,472 Kuroshitsuji vol.10
40, *,548,732 Yotsuba&! vol.9
41, *,547,010 Fairy Tail vol.20
42, *,546,928 Vagabond vol.33
43, *,544,060 Detective Conan vol.69
44, *,543,878 Katekyo Hitman Reborn! vol.30
45, *,541,703 Ookiku Furikabutte vol.13
46, *,539,136 Ookiku Furikabutte vol.14
47, *,536,154 One Piece vol.55
48, *,531,560 Vagabond vol.32
49, *,528,924 D.Gray-man vol.20
50, *,528,271 Fairy Tail vol.21
Manga Ranking Series by Series
*1, 32,343,809 One Piece
*2, *7,409,068 Naruto
*3, *6,572,813 Kimi ni Todoke
*4, *5,739,526 Fairy Tail
*5, *5,204,193 Bleach
*6, *5,165,052 Fullmetal Alchemist
*7, *3,978,439 Gintama
*8, *3,479,219 Katekyo Hitman Reborn!
*9, *3,269,379 Nurarihyon no Mago
10, *3,246,355 Nodame Cantabile
Light Novel Ranking
*1, 1,211,835 Moshidora
*2, *,328,113 Durarara!! vol.1
*3, *,266,030 Durarara!! vol.2
*4, *,237,196 Durarara!! vol.3
*5, *,221,683 Baka to Test to Shoukanjuu vol.7
*6, *,218,081 Durarara!! vol.4
*7, *,215,358 Toaru Majutsu no Index vol.20
*8, *,210,664 Baka to Test to Shoukanjuu vol.7.5
*9, *,199,506 Toaru Majutsu no Index vol.21
10, *,197,573 Baka to Test to Shoukanjuu vol.8
11, *,194,372 Durarara!! vol.7
12, *,182,386 Katekyo Hitman Reborn! Hidden Bullet vol.4
13, *,109,969 One Piece: Strong World
14, *,103,058 Zerozaki Clan vol.7
15, *,102,275 Zerozaki Clan vol.4
16, *,*99,486 Zerozaki Clan vol.5
17, *,*96,730 Zerozaki Clan vol.6
18, *,*92,922 Naruto Dokonjo Shinobu-den
19, *,*78,109 Nurarihyon no Mago vol.1
Source: Oricon
Unlike anime, manga is much more mainstream and we can extrapolate trends and tastes far more reliably than from DVD sales. Here are some observations:
Japan really, really likes One Piece to a degree that I do not think we can really fathom. I mean, when a new volume outsells every other volume released that week combined in a day...
I suspect that FMA sold less than normal, since it ended about halfway into the year and I think a similar explanation holds for Nodame Canatabile, which I'm extremely pleased to see even showing up on this chart.
It pleases me to no end that Kimi ni Todoke is behind only One Piece and Naruto. That's quite an accomplishment, considering it's shoujo and it's not Ouran.
It's interesting to see that Durarara!! got a huge bump because of getting an anime. Its first three volumes are near the top of the chart, beaten only by some light novel about a girl who reads Management: Tasks, Responsibilities, Practices by Peter Drucker. I guess it affected BakaTest and Index to a lesser degree but also notice that it isn't a factor at all for mainstream manga.