You can visit the Social Security Administration's website and search for specific names and their popularity for a given year (including the number of babies born with a particular name).
http://www.socialsecurity.gov/OACT/babynames/
You can use "Popularity of a Name" to get the rank of a particular name or search "Popular Names by Birth Year".
Data from the SSA on the name Tiffany since 2000:
Year of birth Rank 2008 250 2007 212 2006 210 2005 196 2004 175 2003 148 2002 140 2001 127 2000 101
In 2008 there were 1,354 babies born with the name Tiffany. Again this can be found by searching under "Popular Names by Birth Year" and under "Popularity?" selecting Top 500 because "Tiffany" has not been in the Top 100 for the last several years.
There is no exact number available for how many people are named Tiffany, as it varies by region and population data. Tiffany is a popular name in English-speaking countries, particularly in the United States.
Tiffany Seth's birth name is Tiffany Noisworthy.
Tiffany Khamphinuwat's birth name is Tiffany Khampheenuwat.
Tiffany Tynes's birth name is Tiffany Tynes.
Tiffany Chow's birth name is Tiffany Jao.
Tiffany Evans is Tiffany Evans' real name.
Tiffany Brookes's birth name is Ashley Renee Brooke Yeary.
Tiffany Rinehart's birth name is Tiffany Christine Rinehart.
Tiffany Houghton's birth name is Tiffany Crystal Houghton.
Tiffany Dinsmore's birth name is Tiffany Elise McDonald.
Tiffany Dion's birth name is Tiffany Therese Dion.
Tiffany Alvord's birth name is Tiffany Lynn Alvord.