Detailed Instructions: In this task, you're given a passage, further information available on a particular linked term from the statement, and an answer term. Your job is to generate a question that can use the information provided to obtain the given answer. You should use the information on both passage and link information to create the question. Note that the answer to the question should be exactly the given answer, and if the answer is none, the answer to the question shouldn't be obtainable from the passage or linked information.
Q: Passage: Mayer claimed his first victories over United States Army Air Forces (USAAF) four-engine bombers when he shot down two B-17 Flying Fortresses and a B-24 Liberator on 23 November 1942. Together with fellow fighter ace Georg-Peter Eder, Mayer developed the head-on attack as the most effective tactic against the Allied daylight heavy combat box bomber formations. He received the Knight's Cross of the Iron Cross with Oak Leaves on 16 April 1943 after 63 victories. On 1 July 1943, he replaced Walter Oesau as commander of JG2. He claimed his 90th victory on 31 December 1943 and on 5 February 1944 became the first pilot on the Channel Front to reach 100 victories. Mayer was killed in action on 2 March 1944 while leading an attack on a USAAF bomber formation; he was shot down by P-47 Thunderbolt escort fighters near Montmedy, France. He was posthumously awarded the Knight's Cross of the Iron Cross with Oak Leaves and Swords.
Link Information: A higher grade, the Oak Leaves to the Knight's Cross, was instituted in 1940 Answer: 1940
A:
When was the award Mayer received after 63 victories first given out?