The industry of Liechtenstein, limited by shortages of raw materials, is primarily devoted to small-scale production of precision manufactures. The output includes optical lenses, dental products, high-vacuum pumps, heating equipment, electron microscopes, electronic measuring and control devices, steel bolts, knitting machines, and textiles. Pharmaceuticals, electronics, ceramics, and metal manufacturing are also important. The largest industrial companies in Liechtenstein are Hilti (construction services), Balzers (electro-optical coatings), Hilcona (frozen foods), and Ivoclar-Vivadent (dental medical technology). Liechtenstein's industry is completely geared to exports; industrial exports rose from SwFr 196.7 million in 1967 to SwFr3.0 billion in 1996. Around 48% of the labor force is engaged in industry, trade, and construction.