Independence is more difficult in an age when cross-border spillovers of national monetary policy become powerful. These spillover effects make central Banks consider the impact of their policies on foreign and global systems. But it is difficult to pursue global goals when the central bank operates under the narrow, centralized mandate of its independence, and is close to impossible. Mehrotra said the additional rate for PC flash drives in 2017 is about 35 percent, and will increase to 75 percent by 2020. And "a lot of hard drives still need to be replaced by SSDS... Future self-driving vehicles are expected to be equipped with about 40GB of DRAM... This will also drive the use of NAND flash memory." Money sent home by migrants constitutes the second largest financial inflow to many people developing countries, exceeding international aid. Estimates of remittances to developing countries differ from International Fund for Agricultural Development's. Remittances contribute to economic growth also to the livelihoods of folks worldwide.