How many piano trios?

The composer Ludwig van Beethoven wrote a total of 14 piano trios during his lifetime. These include the following works:

- Piano Trio No. 1 in E flat major, Op. 1, No. 1 (1795)

- Piano Trio No. 2 in G major, Op. 1, No. 2 (1795)

- Piano Trio No. 3 in C minor, Op. 1, No. 3 (1795)

- Piano Trio No. 4 in B flat major, Op. 11 (1798)

- Piano Trio No. 5 in D major, Op. 70, No. 1 ("Ghost") (1808)

- Piano Trio No. 6 in E flat major, Op. 70, No. 2 (1808)

- Piano Trio No. 7 in B flat major, Op. 97 ("Archduke") (1811)

- Piano Trio No. 8 in E flat major, Op. 121a (1823)

- Piano Trio No. 9 in B flat major, Op. 121b (1823)

- Piano Trio No. 10 in E flat major, Op. 122 (1823)

- Piano Trio No. 11 in B flat major, Op. 123 (1824)

- Piano Trio No. 12 in E flat major, Op. 124a (1824)

- Piano Trio No. 13 in B flat major, Op. 124b (1824)

- Piano Trio No. 14 in E flat major, Op. 135 (1826)