Thanks for sharing your experience collecting sumo cards. Though I have been a sumo fan since 1999-2000, I did not start collecting sumo cards until 2017-18, beginning with the more recent sets. After finishing 2017 to date, I began to look to collecting all of the sumo cards produced by BBM since their debut release in 1997 since those sets contained rikishi I was familiar with and helped stir my initial interest in the sport. Thinking this should not be so difficult, as the sets were comparatively recently produced, I soon realized that it was not the case. While 1997-2000 are still in good supply, 2001-2003 are much more difficult to build and then the "black hole" of sumo collecting begins with 2004. Cards from 2004 through 2007 are particularly difficult to locate, as BBM sumo card production purportedly dropped significantly during this period--often referred to by advanced collectors as the "Black Hole" or "Lost Years" of sumo card collecting. A possible reason for the 2004-07 scarcity is a decline of Japanese interest in the sport following the retirement of the mega-popular Yokozuna Takanohana in 2003 (after he had two years of frequent kyujo in 2001-02). Also, beginning with the 2004 set, BBM reduced the set size to 99 cards, and discontinued insert cards--an obvious sign of less demand in their Sumo product during that time. I have largely, with the help of the Facebook group: BBM Sumo card collectors, completed all of the base sets from 1997-date. I am still, at the time of this writing, missing 3 cards--all three from the "black hole" period: 2004 #14 and 64 as well as 2005 #65. Additionally, I have accumulated hundred of extras to trade/sell. Please contact me if you can help me finish my 2004 and 2005 sets, or have an interest in getting into the hobby as i can recommend resources, places to find cards and other collectors who can help...