I agree it does matter your location. But it's the overall growth of the sport that is meteoric.
For example on a quick google search:
Top 10 North American PPV buy rates, 2008
- Boxing: Oscar De La Hoya vs. Manny Pacquiao, Dec. 6, 1,250,000
2. UFC: Brock Lesnar vs. Randy Couture, Nov. 15, 1,010,000
- Wrestling: WrestleMania, Floyd Mayweather Jr. vs. Paul â??Big Showâ?? Wight, March 30, 670,000
4. UFC: Georges St. Pierre vs. Jon Fitch/Lesnar vs. Heath Herring, Aug. 9, 625,000
5. UFC: Lesnar vs. Frank Mir, Feb. 2, 600,000
6. UFC: Quinton Jackson vs. Forrest Griffin, July 5, 540,000
7. UFC: St. Pierre vs. Matt Serra, April 19, 530,000
- Boxing: Felix Trinidad vs. Roy Jones Jr., Jan. 19, 500,000
9. UFC: Chuck Liddell vs. Rashad Evans, Sept. 6, 480,000
10. UFC: B.J. Penn vs. Sean Sherk/Tito Ortiz vs. Lyoto Machida, May 24, 475,000
As you can see 7 of the top 10 PPV in NA were MMA events.
But, I agree with you boxing is more popular in some parts of the world than other parts.