You can now save even more money on your file storage – automatically – as your access patterns change when using the Amazon Elastic File System (Amazon EFS) Infrequent Access storage class (EFS IA). Today we’re announcing a 44% reduction* in storage prices for EFS IA, one of the largest percentage price reductions in AWS history to date. EFS IA storage prices now start at $0.025/GB-month. Using the industry accepted estimate that 20% of data is actively used and 80% is infrequently accessed, this reduction leads to an effective EFS storage price of $0.08/GB-month (20% * $0.30/GB-month for files stored on EFS Standard + 80% * $0.025/GB-month for files stored on EFS IA = $0.08/GB-month)*.
from Recent Announcements https://aws.amazon.com/about-aws/whats-new/2019/09/announcing-amazon-efs-price-reduction-for-infrequent-access-storage/