I was interested in this so did a little research. Here are the results
2014 (so far)
Total: 35 planned
2006: 18 (All USA same as previous years)
Some interesting information regarding these.
The 2nd event of 2005 wasn't until April and you guessed it featured Griffin vs Bonnar. The UFC capitalized on the situation doubling its events later that year and the next.
2 years after the TUF 1 finale the UFC went international heading to England and Ireland.
The UFC returned to Ireland in 2009 but since hasn't gone back.
The UFC went to England 7 times in 3 years but in the past 4 years has only returned 5 times. This can be greatly accounted to Bisping's early success and a lack of other top end English fighters making their mark in the UFC.
The UFC has come to Canada 3 times each year for the last 4 years, in large part these coincide with GSP fighting.
The UFC went to Germany in 2009 and 2010 but has not returned since.
Every year except 2009 since 2005 the UFC has increased the number of events it is holding, in 2009 it had the same amount of events as 2008.
In 2011 the amount of USA events peaked and has slowly been declining in the past couple years.
Also in 2011 the UFC went to Brazil for the first time and has seen substantial growth there the last 2 years including the start of TUF Brazil. This past year Brazil has become the only international country to have more then 3 events in a year.
So far in 2014 the UFC has planned more international events then USA events. With increasing international events, increasing overall events and decreasing USA events this may be the first year that there are more international events then USA events.
Overall the UFC has done a great job growing and expanding their product. They receive a lot of criticism on how they handle business at times but obviously it is working and it seems they know what they are doing.
Unseen in these statistics is how the UFC has also shifted from PPV events to televised events. This will only help them in the future as well since people that may have become sick of paying for PPV's will still enjoy watching UFC events if they are on channels they already pay for.