There have been 27 sanctioned 900 series with the United States Bowling Congress as of February 25th, 2015.
The most recent was rolled by Hakim Emmanuel of Brockton, MA on Feb 25, 2015.
The first was rolled by Jeremy Sonnenfeld of Lincoln, Neb. on Feb. 2, 1997. Robert Mushtare of Fort Drum, N.Y. has rolled two 900 series: Dec. 5, 2005, and Feb. 19, 2006.
As of March 27, 2015, there have been 16 sanctioned 900 series in a certified United States Bowling Congress event since July 25th, 2006.
As of February 25th, 2015, there are currently 27 recognized 900 series bowled in sanctioned leagues from the United States Bowling Congress.
Many people have bowled a 300 game. About 26,000 people a year. You can check the USBC website for a listing of sanctioned 300 game bowlers.
It is not a known statistic, however for USBC, you can compare the list of names of who bowled a 300 and how many bowled an 800 and then how many of those who bowled an 800 had a 300.
As of Feb 25th, 2015, there are 27 sanctioned 900 series from the United States Bowling Congress.
Two. One on 10/5/2000 and one on 9/19/2005.
While the USBC (United States Bowling Congress) doesn't keep track of the number of 300s bowled back to back, we know that at least 15 people have been credited with a sanctioned 900 series since 1997 -- a feat that requires three 300s to be bowled back-to-back-to-back. (Make that 16 if you include Glenn Allison's not sanctioned, but widely recognized, 900 shot way back in 1982.) As an informed guess, I'd say that these days several dozen back-to-back 300s are bowled each year; mostly by people who already have several solo 300s under their belt. Ironically, Tom Jordan's record-setting 1198 for four games, achieved in 1989, was NOT one of them: he went 300-299-300-299.
It depends on the organization tracking the information. USBC would have tracking of sanctioned 300 games bowling bowled during sanctioned league or tournament play. CTF would have for Canadian Tenpin Federation. TNBA would have for their association. Etc.
With the advent of high-tech bowling balls and forgiving lane oil patterns, tens of thousands of perfect 300 games are bowled every year. While a good number of them are bowled by people who have already done so at least once, there are still several thousand first-time 300s bowled each year. In fact, as of April 2010, 15 people have officially bowled a 900 series -- which is three 300 games back-to-back in the same league or tournament session. (The actual number of 900s bowled is over 20, but only 15 have been recognized by the USBC.) Fun fact: in duckpin and candlepin bowling, two variations of the sport, no 300s have ever been rolled.
It depends on if you are speaking of sanctioned 300 games by ABC, WIBC and/or YABA or by the PBA. For the earlier, you would need to check the International Bowling Museum / Hall of Fame in Arlington, TX for that data.