A few questions regarding tariifs

First off, let me make this clear that I’m not in support of tariffs, quotas or anything of that nature; I believe in complete and utter free trade.

That said, I did have a few questions regarding some data.

For example, it’s stated here (http://www.heritage.org/index/country/UnitedStates) that the “the weighted average U.S. tariff rate was 1.5 percent in 2008”

Yet the data here (http://stat.wto.org/TariffProfile/WSDBTariffPFView.aspx?Language=E&Country=US) seems to suggest we have higher tariffs (even averaged out) than a mere 1.5%.

Any idea at how they’re arriving at the 1.5% figure?