BOGOTA, May 31(Reuters) - Colombia"s urban jobless rate fell to 17.4% in April, from 23.5% in the same month last year, the government statistics agency said on Monday, based on surveys in the 13 biggest cities. The national unemployment rate was 15.1%, down from 19.8% 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 April 17.4% 15.1% March 16.8% 14.2% February 18.1% 15.9% (Reporting by Bogota newsroom, Editing by Rosalba O"Brien)