Complex sentence: Production of most materials increased as much as 100 percent between 1980 and 1988, but the output of timber for construction declined from 1980 to 1985, before increasing slightly to 433 million units in 1987 and continuing to increase in 1988.
Split into simpler sentences: Production of most materials increased as much as 100 percent between 1980 and 1988. The output of timber for construction declined from 1980 to 1985, before increasing slightly to 433 million units in 1987 and continuing to increase in 1988.