Because they are different years, they get listed separately. However, like other sets that have continuous numbering across series, if you submit an IR on the first set with links to the other sets, Admin can continuous link them and then they can be viewed in one place (even though they remain as separate releases).
-- Dan --
Note: Please see my profile for more info regarding trading (section updated 10/25/2023). I have added a large portion of my inventory to the site, and currently have trading turned off (details are in my profile). I have (finally) unearthed my 2 very large boxes of Star Company minor league sets and they are available (email for details).