Another study conducted by the Philippine Institute for Development Studies, showed that the industry-wide C4 concentration ratio increased from 71% in 1988 to 88% in 1998.

• 另一项菲律宾发展研究协会的研究指出，整个工业大型公司(C4)的集中比率从1988年的71%25增加到1998年的88%25。