You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Namibia

Context:
Since independence Namibia has successfully completed the transition from white minority apartheid rule to parliamentary democracy. Multiparty democracy was introduced and has been maintained, with local, regional and national elections held regularly. Several registered political parties are active and represented in the National Assembly, although the Swapo Party has won every election since independence. The transition from the 15-year rule of President Sam Nujoma to his successor Hifikepunye Pohamba in 2005 went smoothly.

Question:
How long did president Same Nujoma rule?

15-year