Gennady Golovkin was born on April 8, 1982, in the city of Karaganda in the Kazakh SSR, Soviet Union (now Karagandy, Kazakhstan) to a Russian coal miner and Korean mother, who worked as an assistant in a chemical laboratory. He has three brothers, two elder named Sergey and Vadim and a twin, Max. Sergey and Vadim had encouraged Golovkin to start boxing when Golovkin was eight years old. As a youth, Golovkin would walk the streets with them, who went around picking fights for him with grown men.

After ending his amateur career in 2005, Golovkin signed a professional deal with the Universum Box-Promotion (UBP) and made his professional debut in May 2006. By the end of 2008, Golovkin's record stood at 14-0 (11 KO) and while he had few wins over boxers regarded as legitimate contenders, he was regarded as one of the best prospects in the world. Golovkin was given 4 more relatively easy bouts in 2009. In 2010, Universum started to run into financial issues after having been dropped by German television channel ZDF. This caused a number of issues for Golovkin who was effectively unable to fight in Germany, and contract disputes between the two parties got complicated.  Golovkin terminated his contract with Universum in January 2010 and stated the following in an interview: "The reason for this decision is that I've always been placed behind Felix Sturm and Sebastian Zbik by Universum. Our demands to fight against Felix Sturm or Sebastian Zbik have been always rejected on absurd grounds. Universum had no real plan or concept for me, they did not even try to bring my career forward. They would rather try to prevent me from winning a title as long as Sturm and Zbik are champions. Further more, bouts against well-known and interesting opponents were held out in prospect, but nothing happened. This situation was not acceptable. It was time to move forward."  After cutting ties with Universum, the WBA issued an interim title fight between Golovkin, ranked #1 at the time, and Milton Nunez. Golovkin routed Nunez, defeating him in 58 seconds to become a world champion. Golovkin was promptly upgraded to WBA (Regular) champion. He tried to fight WBA (Super) champion Felix Sturm and Hassan N'Dam N'Jikam during this time, but was unable to get them in the ring. Oleg Hermann, Golovkin's manager, said "It is very hard to find a good opponent. Everybody knows that Felix Sturm is afraid of Gennady. Strictly speaking, Sturm should get out of boxing and become a marathon runner because he is running fast and long. He has an excellent chance to become a champion in athletics."

Using a quote from the above article, answer the following question: When did Gennady Golovkin boxing career start?
After ending his amateur career in 2005, Golovkin signed a professional deal with the Universum Box-Promotion (UBP) and made his professional debut in May 2006.