Here's data:
http://www.education.vic.gov.au/Documents/about/research/rea...
Key Findings
* Reading to children at age 4-5 every day has a significant positive effect on their reading skills and cognitive skills (i.e., language and literacy, numeracy and cognition) later in life.
* Reading to children 3-5 days per week (compared to 2 or less) has the same effect on the child’s reading skills at age 4-5 as being six months older.
* Reading to them 6-7 days per week has the same effect as being almost 12 months older.
* Children read to more frequently at age 4-5 achieve higher scores on the National Assessment Program – Literacy and Numeracy (NAPLAN) tests for both Reading and Numeracy in Year 3 (age 8 to 9).
* These differences in reading and cognitive skills are not related to the child’s family background or home environment but are the direct result of how frequently they have been read to prior to starting school.