Nonfuel mineral production in Missouri was estimated at $1.34 billion in 2001, essentially unchanged from 2000. In the same year, crushed stone, portland cement, lead, and lime accounted for 88% of the total value. Crushed stone, by value, has been Missouri's leading nonfuel mineral commodity since 1997, when it surpassed portland cement and lead, the state's 2nd and 3rd top minerals in 2001. Except for several years in the mid-1980s and during 1993–95, lead had been the leading nonfuel mineral since 1969. Restrictions on the use of lead in paint and gasoline, along with prolonged labor strikes, caused lead production in Missouri to decline in the 1980s. Nevertheless in 2001 Missouri was still the nation's top lead producer, contributing well over half the lead produced in the US. The state also ranked 1st in lime and fire clay production, 2nd in iron oxide pigments, 3rd in zinc, and 5th in portland cement. Items of high value in 2001, according to preliminary figures, included crushed stone ($410 million, 75.3 million metric tons); portland cement ($381 million, 5 million metric tons); and construction sand and gravel ($45.4 million, 11.5 million metric tons). Missouri ranked 10th nationally in nonfuel mineral value.