FC Barcelona had a successful start in regional and national cups, competing in the Campionat de Catalunya and the Copa del Rey. In 1902, the club won its first trophy, the Copa Macaya, and participated in the first Copa del Rey, losing 1–2 to Bizcaya in the final. Hans Gamper — now known as Joan Gamper — became club president in 1908, finding the club in financial difficulty after not winning a competition since the Campionat de Catalunya in 1905. Club president on five separate occasions between 1908 and 1925, he spent 25 years in total at the helm. One of his main achievements was ensuring Barça acquire its own stadium and thus generate a stable income.

Answer this question, if possible (if impossible, reply "unanswerable"): When did Joan Gamper become the president of the Barcelona club?
1908