R. B. Gordon, M. Bertram, and T. E. Graedel‘s paper Metal stocks and sustainability in PNAS (Published online 23/01/06)

Shows that copper use per capita is increasing in the US. Increased efficency in use is outweighed by increased consumption. Globally use is increasing much faster than the discovery of new stocks. Below are figures from the article:

Fig. 2. Total per-capita copper stock in use in the U.S. through the 20th century. The GDP of the U.S. from 1929 through 1999 is also indicated.

Fig. 4. Cumulative discovery of copper in ore and the cumulative extraction of copper worldwide in the 18th–20th centuries.