I don't know what the figures were for 1988. Here's some numbers for 1986.
“Of the $387 billion in goods the U.S. imported in 1986, more than 20% was protected by special tariffs, quotas, or other types of restraints, according to Gary C. Hufbauer, a Georgetown University professor. When Reagan took office, the figure was 12%.”
http://money.cnn.com/magazines/fortune/fortune_archive/1987/03/02/68728/index.htm
Surprised?
Why would he be surprised? I’m curious.
That's fascinating. Are you going to try to answer the original question about average tariffs? Just to be clear, what you posted says nothing about average tariffs.