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:
Bern

Context:
Bern has an area, as of 2009[update], of 51.62 square kilometers (19.93 sq mi). Of this area, 9.79 square kilometers (3.78 sq mi) or 19.0% is used for agricultural purposes, while 17.33 square kilometers (6.69 sq mi) or 33.6% is forested. Of the rest of the land, 23.25 square kilometers (8.98 sq mi) or 45.0% is settled (buildings or roads), 1.06 square kilometers (0.41 sq mi) or 2.1% is either rivers or lakes and 0.16 square kilometers (0.062 sq mi) or 0.3% is unproductive land.

Question:
When was the last time the area of Bern was measured?

2009