Breakdown

Publishers with the most entries in the Top 100
Shueisha - 39
Kodansha - 27
Shogakukan - 18
Hakusensha - 6
Kadokawa Shoten - 3

Authors with the most entries in the Top 100
Osamu Tezuka - 5
Rumiko Takahashi - 4
Yoshihiro Togashi - 3
Takehiko Inoue - 3
Naoki Urasawa - 3
Makoto Yukimura - 2

Artists with the most entries in the Top 100

Osamu Tezuka - 5
Rumiko Takahashi - 4
Yoshihiro Togashi - 3
Takehiko Inoue - 3
Naoki Urasawa - 3
Takeshi Obata - 2
Makoto Yukimura - 2

Most entries in the Top 100 by year
This only includes the year the manga started, not completed it's run

1990 - 6

1999 - 6

1998 - 5

1997 - 4

2001 - 4

1989 - 4

2003 - 4

1994 - 4

2007 - 4

2012 - 3

1972 - 3

2014 - 3

1987 - 2

2009 - 2

1982 - 2

2006 - 2

1983 - 2

2005 - 2

2000 - 2

1968  - 2

1976 - 2

1985 - 2

2016 - 2

1996 - 2

1981 - 2

1992 - 2

2018 - 2

1995 - 2

The oldest entry in the top 100
Astro Boy - Osamu Tezuka (Kobunsha) - Rank 30

The newest entry in the top 100
Chainsaw Man - Tatsuki Fujimoto (Shueisha) - Rank 89