PricewaterhouseCoopers (PwC) recently put out its Mine 2015 report, which looks at the top 40 mining companies globally. In it, the firm covers a number of themes in the mining space, including differing points of view on the state of the copper market. PwC notes that copper is the largest contributor to revenues for the top 40 mining companies, making the red metal an important factor in the firm's overall analysis. According to the report, mine production was flat for that group of companies during 2014. Strong performances from Glencore's (LSE: GLEN) mines in Africa were offset by the fact that export restrictions in Indonesia forced Freeport-McMoRan (NYSE: FCX) to curb output from its copper mines in the country. Obstacles to production growth have been present on a larger scale as well. Looking more broadly at the industry, global copper production didn't grow nearly as much in 2014 compared to the year previous (2.6 percent vs 8.1 percent), and PwC notes that Chile, the world's largest copper producer, has faced trouble upping its production due to falling grades. "Production was stagnant due to declining grades, which has forced companies to mine more tonnes and increase processing capacity just to maintain current production levels," the report reads. Furthermore, falling prices have led to a drop in investments in new projects. Citing data from the Peruvian National Society of Mining, Oil and Gas, and Energy, PwC states that mining investments in Peru fell 12.3 percent in 2014. The report also suggests that many mining companies are in "stand-by mode," waiting on prices to improve before deciding to start new projects. Certainly, there are positive signs for supply growth as well. Peru is predicting 10.25-percent growth in copper supply for this year as MMG's (HKEX:1208) Las Bambas comes online and Hudbay Minerals' (TSX:HBM) Constancia mine ramps up. In Chile, Codelco approved a record investment of $3.3 billion late last year to develop the Chuquicamata underground mine.