Dynamic RAM Price Bits per Dollar at Production (Packaged Dollars), DRAM Bits / Dollar, Logarithmic Plot, Page 58

Source:

The ITRS DRAM cost is the cost per bit (packaged microcents) at production.
Data from 1971–2000: VLSI Research Inc. Data from 2001–2002: ITRS, 2002 Update, Table 7a, Cost-Near-Term Years, p. 172. Data from 2003–2018: ITRS, 2004 Update, Tables 7a and 7b, Cost-Near-Term Years, pp. 20–21.