BOGOTA, March 31 (Reuters) - Colombia"s urban jobless rate rose to 18.1% in February, from 11.5% in the same month last year, the government statistics agency said on Wednesday, based on surveys in the 13 biggest cities. The national unemployment rate was 15.9%, up from 12.2% a year earlier, the DANE agency said. The urban jobless rate is more closely watched by financial markets than the national figure. Nearly 70% of the workforce is in large cities. Unemployment figures are not seasonally adjusted and can be volatile, usually depending on factors like peak shopping periods and vacation months. For the full report go to: here Urban National Unemployment Unemployment February 18.1% 15.9% January 19.5% 17.3% December 15.6% 13.4% (Reporting by Bogota newsroom; editing by Jonathan Oatis)