It’s near impossible to give a definitive answer. By the time you add in all the various compilations, reissues, special editions and regional releases, the total number is around the 50 mark (as far as I can tell.)

Perhaps if you were more specific in your question? Is it just releases in one country that you’re after? Or maybe you want to disregard anything other than original studio albums (i.e. not count re-releases, best of, live or other albums.)

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2. A Saucerful of Secrets (June 1968)

3. More (Original Soundtrack Album) (July 1969)

4. Ummagumma (October 1969)

5. Zabriskie Point (Original Soundtrack Album) (January 1970)

6. Atom Heart Mother (October 1970)

7. Relics (May 1971)

8. Meddle (November 1971)

9. Obscured by Clouds (Music from the film ‘The Valley’) (June 1972)

10. Dark Side of the Moon (March 1973)

11. A Nice Pair (April 1973)

12. Wish You Were Here (September 1975)

13. Animals (January 1977)

14. The Wall (November 1979)

15. A Collection of Great Dance Songs (November 1981)

16. The Final Cut (March 1983)

17. Works (November 1983)

18. A Momentary Lapse of Reason (September 1987)

19. Live – Delicate Sound of Thunder (November 1988)

20. Shine on (8CD Boxed Set) (November 1992)

21. The Division Bell (April 1994)

22. PULSE (June 1995)

23. Zabriskie Point (Original Soundtrack Album) – Deluxe Edition (September 1997)

The Piper at the Gates of Dawn (August 5, 1967)

A Saucerful of Secrets (June 29, 1968)

Music from the Film More (July 27, 1969)

Ummagumma (October 25, 1969)

Atom Heart Mother (October 10, 1970)

Meddle (October 30, 1971)

Obscured by Clouds (June 3, 1972)

The Dark Side of the Moon (March 24, 1973)

Wish You Were Here (September 15, 1975)

Animals (January 23, 1977)

The Wall (November 30, 1979)

The Final Cut (March 23, 1983)

A Momentary Lapse of Reason (September 7, 1987)

The Division Bell (March 30, 1994)

The Dark Side of the Moon (1973), Wish You Were Here (1975), Animals (1977), and The Wall (1979)