Yesterday marked the 16-year anniversary of the Oklahoma City bombing – the deadliest terrorist attack on U.S. soil until September 11, 2001.

The April 19, 1995 Oklahoma City bombing in which an explosives-filled truck was detonated outside the Alfred P. Murrah Federal building downtown left 168 dead, hundreds more injured, and still ranks as the ninth worst terrorist attack in terms of insured property losses.

This year also marks the 10-year anniversary of September 11.

A newly updated Insurance Information Institute (I.I.I.) paper notes that nearly a decade later, 9/11 remains the worst terrorist act in terms of fatalities (2,976, excluding the 19 hijackers) and insured property losses (about $23 billion in 2010 dollars).

Today both these terrorist attacks (9/11 and the Oklahoma City bombing) would be covered under the terrorism risk insurance program — a public-private risk sharing partnership that since 2002 has allowed the federal government and the insurance industry to share losses in the event of a major terrorist attack.

The 2007 extension to the terrorism risk insurance program expanded the definition of a certified act of terrorism to eliminate any distinction between domestic or foreign acts of terrorism.

The program is designed to ensure that adequate resources are available for businesses to recover and rebuild if they become the victims of a terrorist attack.

While the Obama Administration has proposed scaling back federal support of the program, the I.I.I. paper cites industry views that the program provides incentive to property/casualty insurers and reinsurers who might not otherwise provide terrorism insurance at current capacity levels or pricing.

Check out further I.I.I. facts and stats on terrorism risk.