LINCOLN, Neb. (AP) – A company tracking robocalls says Lincoln had the biggest one-month jump of the cities studied nationwide in April: nearly 155 percent. The Omaha World-Herald reports that YouMail Robocall Index says robocalling volumes set a record for the second straight month as Americans received 3.36 billion calls in April. That’s 6.5 percent higher than in March and 34.4 percent higher than April last year. A distant second to Lincoln was Southfield, Michigan, where call volume increased 85.4 percent. The YouMail Robocall Index tracks the calls to iPhones, Androids and landlines. Its statistics are cited by the Federal Communications Commission for national data trends. The company says the most common reason for robocalls nationally in April was debt collection. Student loan collection was the most common reason in Nebraska.