The variability of the blazar Markarian 421 in TeV gamma rays over a 14-year time period has been explored with the Whipple 10 m telescope .
It is shown that the dynamic range of its flux variations is large and similar to that in X-rays .
A correlation between the X-ray and TeV energy bands is observed during some bright flares and when the complete data sets are binned on long timescales .
The main database consists of 878.4 hours of observation with the Whipple telescope , spread over 783 nights .
The peak energy response of the telescope was 400 GeV with 20 % uncertainty .
This is the largest database of any TeV-emitting active galactic nucleus ( AGN ) and hence was used to explore the variability profile of Markarian 421 .
The time-averaged flux from Markarian 421 over this period was 0.446 \pm 0.008 Crab flux units .
The flux exceeded 10 Crab flux units on three separate occasions .
For the 2000–2001 season the average flux reached 1.86 Crab units , while in the 1996–1997 season the average flux was only 0.23 Crab units .