SELECT AVG(year) FROM table_name_19 WHERE issue_price__proof_ = "$49.95" AND artist = "w.h.j. blakemore"
Berapa tahun rata -rata dengan harga (bukti) $ 49,95, dan artis W.H.J.Blakemore?
CREATE TABLE table_name_19 (year INTEGER, issue_price__proof_ VARCHAR, artist VARCHAR)