In the 1970's, approximately 80 percent of a company's value was in tangible assets, such as buildings, real estate, equipment, cash, and inventory. Today, a company's tangible assets typically accounts for only about 20 percent of a company's book value. During the same time period, the total number of patent applications filed at the US Patent and Trademark Office has grown by nearly 500%, from 107,456 in 1975 to 520,277 in 2010.