question: What's the average Year with an Issue Price (Proof) of $49.95, and Artist of W.H.J. Blakemore?
answer: SELECT AVG(year) FROM table_name_19 WHERE issue_price__proof_ = "$49.95" AND artist = "w.h.j. blakemore"
context: CREATE TABLE table_name_19 (year INTEGER, issue_price__proof_ VARCHAR, artist VARCHAR)