score:1
On Bible Hub or in any physical copy of the Bible, "roughly in the middle" (thanks @curiousdannii).
David is specifically denoted the author of 75 of the 150 Psalms, which are listed here, on GotQuestions. The others have no mention or limited background information so we are uncertain, and others are written by other people. 73 are listed specifically in Psalms as being a psalm of David, and 2 (Psalm 2 and 95) are mentioned in the New Testament as being written by David (see Acts 4:25, Hebrews 4:7). Because of this, it seems reasonable to conclude that David wrote some-many of the other "anonymous" Psalms, but just that his name isn't listed.
As for as other authors of the psalms in the Book of Psalms, here is a short discussion. Other authors include:
Asaph (and family) (12 psalms): 50; 73—83
The sons of Korah (11 psalms): 42; 44—49; 84—85; 87—88
Heman (1 psalm, with the sons of Korah): 88
Solomon (2 psalms): 72 and 127
Moses (1 psalm): 90
Ethan the Ezrahite (1 psalm): 89
And comment by @MattGutting said that Psalm 151 is in the Orthodox Bible, as apparently that isn't in other Bibles. I don't know anything about that.